JPS5982194A - Coating method of flux on covered arc welding rod - Google Patents

Abstract

PURPOSE:To perform smooth and stable continuous coating with a screw extruder by specifying the ratio of the shaft diameters of the screw in a feed zone and a constant volume feeding zone for the flux as well as the ratio between the shaft diameter and the outside diameter of a screw blade respectively. CONSTITUTION:A screw 1 which consists of a shaft 1a and a blade 1b and constitutes a feed zone (a), a compression zone (b) and a constant volume feeding zone (c) for a flux F is provided in a cylinder 2 to increase stepwise the degree of compression of the flux F. A core wire 6 inserted in a die block 3 through a nipple 5 is extruded together with the flux F from a die 4 thereby forming a coated arc welding rod. The ratio d1/d2 between the shaft diameter d1 of the screw in the zone (a) and the shaft diameter d2 of the screw in the zone (c) of said screw 1 is set at 0.7-0.9 and the ratio d1/D between the shaft diameter d1 of the screw in the zone (a) and the outside diameter D of the screw blade is set at 0.4-0.8, and the ratio d2/D between the diameter d2 of the screw in the zone (c) and the outside diameter D of the screw blade is set at 0.6-0.8.

Description

[Detailed Description of the Invention] The present invention relates to a method of coating flux on 6-gauze (hereinafter referred to as "silver wire") for coated arc welding rods using a screw extrusion method, and in particular, the flux does not generate heat during extrusion. By doing so, it is possible to prevent the curing phenomenon and ensure necessary and sufficient discharge pressure, thereby increasing the stability of the coating and fully demonstrating the effect of continuous coating.

・When applying flux to the core wire, the so-called plunger extrusion method is generally used, in which a flux cake made by kneading the flux components and further molding is inserted into a cylinder and extruded together with the core wire from a die at the tip of the cylinder. has been done. However, in the plunger extrusion method, from the end of one extrusion to the start of the next extrusion, coating is completely stopped in order to fill the cylinder with new flux cake, resulting in so-called idle time (non-operating time). This poses a problem in terms of productivity.

Therefore, in order to improve productivity, there is a strong demand for a coating method that does not cause idle time as described above, and as one such method, the adoption of a continuous extrusion method using a screw has been proposed. ing. However, in order to enjoy the advantages of this method, it is necessary to ensure that the forward movement of the extruded material is carried out in accordance with the rotation of the screw. However, the material to be extruded has extremely poor fluidity like flux, and the temperature rises (about 40 to 50 degrees Celsius or higher).
If the material is one that begins to harden quickly, it is difficult to maintain stable continuous extrusion unless the extrusion operating conditions are set to the optimum conditions. Furthermore, in order to reliably apply a constant amount of flux to the core wire, the pressure of the input flux is increased in the cylinder in small steps to the extent that the flux in the die block at the tip of the extruder can exert a constant discharge pressure. There is also a need. However, since the screw extrusion method that satisfies these requirements has not yet been developed, coating methods using the screw extrusion method have not been put into practical use.

The present invention was made under these circumstances, and its purpose is to completely prevent the phenomenon in which flux heats up and hardens during screw extrusion, as well as to maintain the necessary and sufficient discharge pressure.
The object of the present invention is to provide a flux coating method that can perform partial coating smoothly and at a constant V by ensuring that the coating is maintained.

However, the coating method of the present invention, which has achieved these objectives, has a screw in which the pitch of the blades is constant and the diameter of the shaft increases toward the tip end. When applying flux to the coated arc #contact rod using a screw extruder, which has a supply section, a compression section, and a quantitative supply section sequentially formed from the upstream side of the screw shaft diameter in the supply section and the The ratio of the screw shaft diameter in the quantitative supply part is set to 0.7 to 0.9, and the ratio of the screw l1lliI diameter to the screw blade outer diameter in the supply part is 0.4 to 0.7, and the quantitative supply part The gist is that the extrusion is carried out in a rectangular manner so that the ratio of the screw shaft diameter to the root outer diameter of the screw 518 is 0.6 to 0.8.

The structure and operation of the present invention will be explained below based on the drawings of the embodiments.
The progress and results of the experiment will be explained and explained. Figure 1 is a schematic vertical cross-sectional view of the screw extruder used in the flux coating experiment of the present invention, where 1 is the screw, 2
A cylinder with a Fi screw l inside, 8 is a die block attached to the tip of cylinder 2, and 1
) is the outer diameter of the screw blade, ■, ■, θ are the flux F
supply section, compression section, quantitative supply section, Pl s P 2
* P 3 is the pitch of the screw blades at each of these parts [P 1 = P 2 z P 3 = P c (
(constant pitch)], dl indicates the screw shaft diameter in the supply section (2), and d2 indicates the screw shaft diameter in the quantitative supply section θ.

That is, in the figure, the screw extrusion part is the screw blade 1b.
The pitch is a certain amount, and the shaft diameter increases on the tip side (
dl<d2) By installing the screw 1 in the cylinder 2, the above-mentioned parts (A), @, and θ are formed in the cylinder 2 in the order of the flow direction of the flux °F. Therefore, although the groove width of the screw τ1 is constant, the cross-sectional area surrounded by the screw shaft outer diameter and the cylinder inner diameter becomes smaller as it goes toward the tip. It is configured such that the degree of compression increases at each stage as it is transferred to the quantitative supply section θ.

Further, the flux F introduced into the cylinder 2 from the supply section is sent toward the die block 8 by the rotation of the screw 1. The die block 8 is provided with a die 4 at the outlet, and a core wire guiding nipple 5 is inserted concentrically with the die 4, and the core wire 6 fed from the nipple 5 is guided by a flux F. At the same time, by extruding from the die 4, the outer periphery of the core wire is coated with flux F, and a coated arc welding rod is manufactured.

In order to smoothly perform continuous coating of flux F using the extruder configured in this way, (1) the flux F introduced from the supply section ω must be reliably transferred to the inside of the die block 8 by the screw 1; At the same time, the condition (2) that the pressure of the flux F in the die block 8 is raised to a pressure that allows the core wire to be pulled out from the nipple 5 and reliably discharged from the die 4 must be met at the same time. By the way, it can be said that the condition (11) is basically a problem of axial torque in the screw 1, and the condition (2) is a problem of the degree of compression of the flux when the screw I is rotated.

Therefore, the present inventors (in investigating a technical means that can satisfy the condition 11) found that the ratio (d
1 / d2), and for condition (2), the ratio of the screw shaft diameter to the screw blade outer diameter (d1/I)) in the supply section and the ratio (d1/I) in the constant supply section. This was done by changing various combinations of the ratio of the screw shaft diameter to the screw blade outer diameter (d2/D).

As a result, (a) data shown in FIG. 2 was obtained when d1/d2 was larger than 0.7 to 0.9. Ml] FIG. 2 is a graph showing the change in flux discharge pressure over time in the case of d17d2=0.95, and the following can be understood from this graph. Since the depths of the grooves in the supply section (2) and the quantitative supply section (C) are approximately equal, the degree of compression is extremely small, resulting in a function similar to that of a so-called screw conveyor. Therefore, L
) The discharge pressure required to draw i6 from the nipple 5 while painting (generally the water contained in the flux,
Welding rod size, die block shape, etc. may vary, but 30
0~5 Q Okg/am".Hereinafter referred to as "Required H:
extrusion coating is not possible.

On the other hand, (b) when d1/d2 was smaller than 0.7 to 0.9, the data shown in FIG. 8 was obtained. That is, Fig. 8 is d
Flux discharge pressure in the case of 1/d2=0.6,
A graph showing changes in discharge amount and discharge fM degree over time,
From this graph, the following can be solved by flJJ. In other words, although the supply capacity of the flux F in the supply section ■ is sufficiently stable, the degree of compression from the compression section @ to the quantitative supply section O is too high, so that the supply capacity in the supply section ■ is equal to the supply capacity in the fixed quantity supply section θ. will exceed. As a result, heat generation increases especially in the metered supply section O, and the water content in the flux F decreases, resulting in tight slippage between the screw L and the flux F, and the flux F bridges in the compression section ◎ and the metered supply section θ. cause a phenomenon.

For this reason, extrusion coating is only carried out intermittently, and furthermore, the effects of heat generation result in products of poor quality with a rough coated surface. Furthermore, if dl becomes smaller, a large load will be applied to the shaft relative to the proportion of the extrusion capacity, and the screw IIIi11a will become very likely to break.

On the other hand, (c) d1/dg is 0.7 to 0.9 +7
), data indicating the 4th section IK was obtained.

In other words, Fig. 4 is a graph showing changes in flux discharge pressure, discharge amount, and discharge temperature over time in the case of d1/d2 = 0.85, and there is almost no heat generation and the discharge pressure almost reaches the required pressure. It is easy to understand how it is stable and the discharge amount is also stable.

Therefore, it is clear that there is no roughness in shaft torque at all.

Next, maintain d1/d2 at 0.7 to 0.9FC,
When d1/D was set larger than 0.4 to 0.7, the data shown in FIG. 5 was obtained. That is, Figure 5 udl/
This is a graph showing the ashing of flux discharge pressure and discharge amount over time in the case of d2=0.7 and dl/D=0.8, and the following can be understood from this graph. That is, since the groove depth of the screw becomes shallower, the supply range of fuwax F decreases accordingly. Therefore, the flux F in die block 8
The die is in a state where it is periodically pressed, and when the die discharge pressure has reached the required pressure, it is intermittently turned back.

The 1ζ extrusion coating will also be intermittent.

On the other hand, (e) maintaining d1/dz at 0.7 to 0.9,
When dl/D was set smaller by 0.4 to 0.7, the data shown in FIG. 6 was obtained. That is, the 6th 1i, i
This is a graph showing changes in flux discharge pressure and discharge amount over time in the case of d 1/d 2 to 0.7"t'd l/D=0.8. From this graph, the following can be understood. Rlj The depth of the screw becomes even deeper (because
The supply range of flux F increases accordingly, and the compressive force acting on flux F increases significantly (as a result, heat generation increases (the discharge temperature curve is omitted in the figure).
. Therefore, the moisture content in the flux decreases rapidly, and the lubricity between the screenie L and the flux F rapidly decreases.
and these will rotate as one, so
As the situation progresses, the entrainment discharge pressure drops below the required pressure, making extrusion coating impossible.

On the other hand, g) d l / (12 to 0.7・0.
When dl/D was maintained at 9 and 0.4 to 0.7, the data shown in Figure 7 was obtained. In other words, Fig. 7 shows (11/dz=0.7 and dl/D20.5
This is a graph showing changes in flux discharge pressure and discharge amount over time in the case of I understand.

However, even if the above extrusion conditions are set, depending on the value of d2/D, it may not be possible to maintain a stable state.
- It has been found that stable conditions for extrusion coating are formed only within the range of pheasants.

That is, ()) d 2 / D was set to be larger than 0.6 to 0.8, and the data shown in Fig. 8 was obtained. In other words, Fig. 8 shows the case when dl/D = 0.9. This is a graph showing changes over time in flux discharge amount and discharge temperature.The following can be understood from this graph.In other words, in the quantitative supply section O, the flow path cross-sectional area of flux F decreases, so when the screw rotates 10 times. If the number is reduced to one, the discharge efficiency will decrease.Also, from the beginning of operation, the temperature of the discharge 1M degree tends to rise (60 to 70 degrees).
(°C), so we cannot expect much from the quality of the product.

On the other hand, when (g) d2/D was set smaller than 0.6 to 0.8, the data shown in FIG. 9 was obtained.

That is, FIG. 9 is a graph showing temporal changes in fuwax discharge pressure, discharge pattern, and discharge temperature in the case of d 2 /D -0.5. In this case, the flux F is hardly compressed, so that the discharge pressure is only about half of the required pressure, and not only the discharge amount is extremely small, but also the extrusion 49- cannot perform any loading.

On the other hand, when (S)d2/D was set within the range of 0.6 to 0.8, the data shown in FIG. 10 was obtained.

In other words, Fig. 10 is a graph showing the flux discharge pressure in the case of (11/D = 0.65), the discharge amount, the discharge knitting density, and the change over time, and this graph shows that there is almost no heat generation (the discharge temperature is 80 ℃ it), the discharge pressure is stable at almost the required pressure, and the discharge volume is also stable at almost the sufficient level.Therefore, extrusion coating is performed continuously, and high-quality products are produced. You can get it by doing this.

Based on the experimental support for (a) to (s) above, o, 74
d engineering/d2 (-0.9FC setting, 0.4≦d
The present invention has been achieved in that a good coated product can be continuously obtained by performing extrusion with settings such that l/D≦0.7 and 0.6≦d2/D≦0.8. This is what I did.

As long as an improved foot operation range can be secured, it is a good idea to appropriately design and implement the supply section, die block S, etc. of the extruder, as well as the incidental parts of the extruder.

Since the present invention is constructed as described above, continuous flux mounting can be performed stably, idle time is eliminated, and productivity can be improved.

In addition, since the flux does not generate heat during continuous extrusion, smooth coating is possible without reducing the moisture content in the flux, and the quality of the coated arc welding rod product is maintained in good condition. can do.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram illustrating the flux coating method of the present invention, and FIGS. 2 to 10 are graphs showing the results of 11) 1 coating tests of the present invention. l...Screw 2...Rinda 8...Die block D...Outer diameter of screw blade ■...Supply section @...Compression section O...Quantitative supply section! 'l, P2. P3...Screw blade pitch dl+
d2...Screw shaft applicant Kobe Steel, Ltd.

Claims (1)

[Claims] 11) By installing a screw in the cylinder in which the pitch of the blades is constant and the l1IIIl diameter becomes larger on the tip side, a supply section, a compression section, and a quantitative supply section are sequentially installed in the cylinder from the upstream side of the extruded material. When applying flux to the formed ID wire for arc welding rods using a screw extruder, the ratio of the screw shaft diameter in the supply section to the screw shaft diameter in the quantitative supply section is set to 0.7 to 0. ．．
9, and the ratio of the screw shaft diameter to the screw blade outer diameter in the supply section is 0.4 to 0.7, and the ratio of the screw shaft diameter to the screw blade outer diameter in the quantitative supply section is 0.6. A method for coating a coated arc welding rod with flux, the method comprising performing extrusion at a flux setting of 0.8 to 0.8.