UA35173A - Methods for producing powder wire - Google Patents

Abstract

The invention relates to the methods of producing the welding materials. Preliminarily the dimensions of cross section of ascending tape are calculated, a chute is formed from the moving tape, during motion it is filled with powder charge, the chute is closed with formation of tubular billet and the billet is drawn several times in two stages to required diameter.

Description

The invention relates to methods of manufacturing welding materials, or more specifically, flux-cored wire intended for welding and surfacing.

Powdered wire occupies one of the leading places among electrode materials used in modern electric arc welding processes. The technological process of its production includes a number of operations that are performed simultaneously - the formation of a metal strip into the initial wire blank (sheath) in calibrated rollers with charge filling and subsequent repeated drawing of the billet on a drawing machine to obtain a wire of the required diameter.

Various methods of manufacturing flux-cored wires are known, which consist of a metal shell and a powder-like flux filler, during which the metal strip is given the shape of a chute, the chute is filled during movement with a powder-like flux mixture - a charge, the chute is closed to form a tubular blank and it is drawn to the required diameter ( Pokhodnya, I.K., Alter, V.F., etc. "Production of flux-cored wire", Kyiv, Higher School, 1980, p.232).

Depending on the purpose of the powder-coated wire and the technological requirements for it, the filling of the cavity of the chute is performed completely or partially

Filling the entire volume of the cavity of the tubular billet significantly worsens the conditions of deformation of the wire during its drawing. The compacted charge provides additional resistance to the plastic deformation of the metal shell, which leads to a rapid loss of plastic properties of the wire, limits its ability to deform during drawing, reduces the reliability of the drawing process and its productivity.

During the production of tubular wire, the tape is pre-stretched through guide and forming rollers, which have corresponding calibration grooves, while intermediate profiles are formed (including a trough-shaped one, filled with charge). As a rule, the frequency of such previous tape bending operations is no more than 2-3, therefore, during each bending, the tape is exposed to significant deformations that change its shape rather sharply at each stage of bending. Such a technological process requires the use of durable profiling equipment and causes the consumption of a significant amount of energy to pull the tape through the forming device, which increases the cost of manufacturing powder-coated wire as a whole. Sharp bends of the tape during the forming of the chute cause additional resistance to the drawing of the workpiece through the forming rollers of the forming device.

There is a well-known method of manufacturing powder-coated wire, during which the chute is incompletely filled with a charge - in the amount of 5-65950 from the volume of the tube cavity, and the drawing of the tubular blank is performed with a total crimping of 20 - 40 95 (Ass. USSR Meo992145 MKVb V2ZK 35/36 from 18.10.7vr "Method of manufacturing powder-coated wire", I.K. Pokhodnya, V.F. Alter, V.V. Golovko, Published by B.I. Mo4, 1983)

The disadvantage of this method is that the incomplete filling of the tube cavity leads to an uneven distribution of the charge inside the closed cavity and, as a result, to uneven compaction of the charge during the deformation of the wire during drawing and uneven hardening of the metal shell due to this phenomenon, which quite often leads to wire breaks during dragging and makes this process unstable.

The practice of making wire using this method proves that on a wire that is made in the range of the most frequently used values of partial filling of the tube cavity at 40-6595, with single crimps of 20-459565, the maximum possible total crimp is 70-8595 At this level of single crimps after reaching a total crimp of 70-8595 (depending on the initial plastic properties of the tape), further drawing of the wire is practically impossible, although the plasticity resource of the shell is not yet exhausted. At the same time, if we use metal tapes with a ratio of width to thickness from 18 to 30 (0.4x10; 0.5x12; 0.7x13; 0.3x8) as risers, these are the most common cross-sectional sizes of tapes in the world for production of powder-coated wire), then such total crimps are not enough to obtain powder-coated wire with a diameter of 1.2 mm and less. This is impossible because the low-plastic wire cannot be pulled during the last transitions with single crimps in 20-45905. The sheath simply cannot withstand such loads and breaks.

For the prototype of the claimed invention, a method of manufacturing powdered wire is selected, during which the dimensions of the cross-section of the rising belt are calculated in advance, a chute is formed from the moving belt, it is filled with a powder charge during movement, the chute is closed to form a tubular blank and drawn repeatedly workpiece to the required diameter in two stages (As. USSR Meo1532255

MKYb B 23K 35/368, dated 11.08.87. "Method of manufacturing powder-coated wire" I.K. Pokhodnia, V.F. Alter,

Pub. BI Mo48, 1989). The ratio of the width to the thickness of the tape in this method was equal to 20, the total level of deformation was equal to 85-9595.

The technological process of wire production according to the present invention is divided into two stages, in the first of which drawing is carried out with single crimps 20-4595 until the overall crimp level is reached 70-8595, and during the second stage, the wire obtained during the first stage is drawn with single crimps crimps 5-1595 so that the total crimping for two stages was 85-9595.

However, even this method has a number of significant drawbacks.

As with all the above-mentioned methods of preparing flux-cored wire, during the application of the existing method, the tape, which has an ascending rectangular profile, turns into a trough with vertical walls for its subsequent filling with the charge. During such a sharp change in shape in 2-3 bending operations, it is very difficult, and often impossible, to achieve a uniform distribution of the load in each form-forming gauge and to achieve a stable orientation of the profile in it relative to the vertical axis. In addition, as mentioned above, this method of forming requires the use of rather massive forming equipment and unproductive expenditure of energy for bending and bending the tape during its movement.

During the drawing of a tubular billet, the cavity of which is filled with 40-6595 at the first transitions of the first stage, when the reduction of the cross-section of the wire occurs only due to the stretching of the shell without sealing the charge in the middle of the cavity, at the entrance of the tubular billet to the deformation center with single crimps 20-4595 the effect of swelling and opening of the edges of the tape takes place. The length of the section of the puffing and opening of the edges is equal to 0.5-2 diameters of the wire that is included in the drag.

For the uniform entry of the workpiece into the draw without the danger of opening the edges, the condition of matching the degree of its elongation to the compressive force in the draw must be met. In this case, the ratio of tape sizes is insufficient for single crimps 20-4595, so this condition is violated.

As a result of the violation of the degree of elongation of the workpiece with the level of compressive forces, swelling and opening of the longitudinal joint of the workpiece takes place, drawing (soap) grease gets into the middle of the wire, which significantly worsens the welding and technological properties of the finished wire. In addition, in practice, in the middle of the cavity of the tubular billet, overflow of the charge often occurs, which occurs even due to minor and uncontrolled fluctuations in the thickness of the charge layer in the moving chute. This leads to uneven deformation of the wire and its uneven longitudinal tempering, as a result of which the breakability of the wire increases in the second stage of drawing. Another reason for the fluctuation of the thickness of the charge layer in the middle of the wire in the first passes of the first stage of drawing is the sharp acceleration of the wire movement in the center of deformation with single crimps 20-4595, which leads to frequent breaks in the wire.

The next disadvantage of the invention is that the wire blank at the first transition of the first stage of drawing often twists around its axis, sometimes even bends, which can also lead to the opening of the longitudinal joint and the discharge of the charge through the gap in the zone of closing the edges of the tape. This happens because the workpiece prepared for drawing on the approach to the first die has the shape of a circle, which is difficult to keep in one position in exact accordance with the technological axis with the fixation of the longitudinal joint at the upper point of the cross section of the workpiece.

The basis of the claimed invention is the task of increasing the efficiency of the method of manufacturing powder-coated wire by choosing the optimal dimensions of the tape and the configuration of intermediate profiles, establishing optimal ratios of the degree of deformation of the workpiece and compressive and tensile forces that act on the workpiece during its shaping, which allows to reduce the amount of the longitudinal force acting on the tape when profiling the groove profile of the workpiece, to ensure the uniformity of the distribution of the load in each forming gauge and to match the degree of stretching of the tape with the compressive force acting on the wire in the drawing, as well as to avoid the torsion of the workpiece around its axis during profiling and the first drawing pass.

The problem is solved by the fact that in the method of manufacturing powdered wire, during which the dimensions of the cross section of the ascending belt are calculated in advance, a chute is formed from the moving tape, it is filled with a powder charge during movement, the chute is closed to form a tubular blank, and the billet is drawn repeatedly to the required diameter in two stages, according to the invention, the dimensions of the cross-section of the tape are selected from the ratio of width to thickness in the range of 8-15, the formation of the trough is performed by repeatedly bending the edges of the tape at an angle of 10-15 degrees for each bending, the tubular workpiece in the cross-section is given the shape of an ellipse, the vertical axis of which is formed 1.05 - 1.15 times longer than its horizontal axis, the first drawing pass at the first stage is performed with single crimping 13-1995.

In addition, before the beginning of drawing the tubular blank, which has the shape of an ellipse, the closed edges of the tape are heated to the melting temperature of the edges and then the ellipse is deformed into a circle with the formation of a thermomechanical welded joint of the edges in the area where the edges of the tape are closed.

The figure shows the appearance of intermediate profiles during the process of sequential forming of a wire of a tubular structure at each of the technological operations.

Fig. 1 shows a section of the tape in the initial state.

Fig. 2 - Fig. 7 show intermediate sections of the workpiece during the formation of the trough-shaped profile.

Fig. 8 shows the stage of transformation of a trough-shaped profile, which is filled with a charge, into an oval blank with the vertical axis of the oval A and the horizontal axis B.

A feature of the invention is that the ratio of the width of the tape, which is used for the production of wire according to the proposed method, to its thickness exceeds that in the prototype method, and the size of single crimps on the first pass of the first stage of drawing, on the contrary, is slightly reduced. This makes it possible to eliminate the disadvantages that arise during the drawing of the tape through the forming device and the drawing machine, described in the prototype - the swelling and opening of the joint of the edges of the tape and the brokenness of the wire, as well as to reduce the effort that must be spent for the production of powder wire.

The ratio of the width of the tape to the thickness in the range of 8-15 allows to increase the proportion of metal in the tubular billet, and the reduction of single crimps to the level of 13-1995 makes it possible to make a slower entry of the billet into the first die, improving the conditions of deformation during the elongation of the shell. This allows to reduce the drawing force and optimize the acceleration of the wire movement in the deformation center.

In other words, the combination of the dimensions of the proposed tape with the amount of compressive forces affecting the tubular blank formed from it prevents swelling and opening of the joint of the closed edges of the tape.

If the width-to-thickness ratio of the tape is set to more than 15, then its dimensions will be reduced to accept the set compressive forces, and negative phenomena that occur in the known invention (opening of the edges of the tape) may occur during drawing.

Choosing this ratio less than 8, the dimensions of the tape will be unreasonably increased both for the perception of crimping and for the formation of an optimal profile in the intermediate operations of bending the tape.

The next exception to the proposed method is to uniformly bend the edges of the tape at an angle of 10 to 15 degrees for each operation. In the known invention, there is a sharp transition from a flat tape shape to a trough-shaped one with a minimum number of transitions - with an uneven load on the gauges in each transition.

As can be seen from Fig. 2-7 of the claimed invention, both edges of the tape in the grooves of the calibration rollers are uniformly bent at an angle of 10-15" along the axis of the tape at each bending operation, which allows you to consistently form a given profile. Deformation of the tape begins in the axial section profile and increases smoothly, without sharp transitions. It should be noted that in the proposed method, the number of bending operations until the chute is filled with charge is slightly increased compared to two or three in the prototype invention. But this is not a drawback, but a significant advantage of the proposed technical solution , because the smooth bending of the edges of the tape allows you to significantly reduce the deforming and longitudinal forces, and as a result, the power and metal capacity of the entire device for bending and stretching the metal tape. The advantage of the smooth shape change of the profile is also that the stability of the tape in gauges with a uniformly increasing angle of inclination of the side walls significantly higher than in the known invention.

The difference of the invention is also that the cross-section of the tubular workpiece after the operation of closing the edges has the shape of an ellipse (Fig. 8), and not a circle, as in all known technological processes for the production of flux-cored wire.

An elliptical workpiece is easier to fix in one position. It is not subject to rotation around its axis, therefore, in the process of manufacturing the wire, according to the claimed invention, there is no opening of the longitudinal joint. The dimensions of the axes of the ellipse were chosen based on the conditions of ensuring uniform wear of the inner surface of the input die of the drawing machine, as well as the correspondence of the degree of deformation of the shell to the tensile force.

On the basis of experiments, it was established that the most favorable conditions for drawing elliptical blanks in the first draw occur when the vertical axis A of the ellipse exceeds the value of the horizontal axis B by 1.05-1.15 times.

In this case, the shape of the ellipse is slightly elongated and at the same time as close as possible to a circle, which not only prevents the workpiece from twisting, but also ensures that it is evenly gripped by the surface of the technological lubricant when entering the die

If the vertical axis exceeds the size of the horizontal by less than 1.05 times, the dimensions of both axes will be practically equal and the section will take on a shape close to a circle, that is, it will be almost the same as in the prototype.

Exceeding this ratio by more than 1.15 times is also unjustified, because the ellipse in this case will become too elongated along the vertical axis, which will create additional obstacles to the entry of the wire into the first die and increase the resistance of the workpiece to deformation.

Additional heating of the closed edges of the tape before the entry of the elliptical blank into the first draw and the formation of a thermomechanical welded joint in the area where the edges of the tape are closed ensures the sealing of the inner cavity of the wire. Sealing provides the wire with a number of additional positive properties - complete elimination of the possibility of charge shedding during processing and use of the wire, improvement of the quality of welding seams due to the prevention of moisture penetration into the charge, an almost unlimited period of use of the wire, the possibility of applying a thin copper coating to the surface of the wire by galvanic means for improvement of power supply conditions and others.

The method is carried out as follows:

Profiling of the tape for the production of powder wire is carried out in a profile bending device, where the tape is gradually drawn through the guide and working rollers in accordance with the calibration. At the same time, intermediate profiles (Fig. 2-6) appear, including a grooved one, filled with a powder-like filler (charge), which comes from a dispenser installed on the profile-forming device. For uniform distribution of filler components over the entire volume of the cavity of the tubular blank and along the entire length of the wire, the cavity of the tubular blank is filled with a charge of 100905.

The wire enters the drawing stage in the form of a workpiece rolled into an elliptical tube, the cavity of which is filled with an uncompacted mixture of powdered filler (Fig. 8). 1-10 cm movement of the workpiece). In the first drawing, the wire is calibrated - ovality, burrs are eliminated, and the technological lubricant is captured on the surface of the wire.

When the wire passes along the entire drawing route in the working zone of the die, it is deformed, in the process of which the cross section of the wire is reduced to a given diameter. The finished wire is taken on a coil using a special device at the end of the technological line

Examples of specific execution of the method.

Powdered wire with a diameter of 1.2 mm with a filling factor of 1295 was produced from a cold-rolled strip of low-alloy steel. Below are the parameters of the technological process modes, which were changed within the limits provided by the claims of the invention, and the results of the described actions.

Example 1. A tape with a width of 12 mm, a thickness of 1.5 mm, with a cross-section ratio of 8 was used.

During the formation of the trough-shaped profile, the edges of the tape were gradually bent to an angle of 107 for each operation. The vertical axis of the elliptical cross-section of wire blank A exceeded the horizontal axis B by 1.05 times. In the process of forming a trough-shaped profile, the pulling force was equal to approximately 0.8 tons, since a lower level of force is not enough to bend the tape of the indicated sizes. The reshaping of the elliptical shape of the wire in the first drawing pass at the first stage was performed with crimping 1395.

The practice of manufacturing powder-coated wires shows that at the level of pulling forces, more than 6.5 tons, the level of technical and economic indicators of the entire cycle of wire manufacturing (from the beginning of the formation of the initial blank to the receipt of finished products) begins to decrease. Therefore, we accept the following dimensions of the tape and the parameters of the mode of its transformation into a wire of a given diameter as the limit below which the wire manufacturing process becomes unprofitable.

Example 2. A tape with a width of 12 mm and a thickness of 0.8 mm was used with a ratio of these dimensions of 15. The edges of the tape were bent at an angle of 15" each time, and the ratio between the major and minor axes of the elliptical cross-section of the workpiece was equal to 1.15, that is, the shape of the ellipse is more elongated along vertical axis, in comparison with the one considered in the previous example. The workpiece at the first stage of the first stage of drawing was crimped to 1995, the pulling force at the same time was equal to 0.6t.

Despite the fact that the thickness of the tape is less than in the previous case (which even improved the conditions for its bending in the chute), it was noticed that when the elliptical workpiece was passed through the first drag, when the pulling force was equal to 0.bt, uneven gripping of the technological lubricant sometimes began surface of the workpiece. It follows from this that further reduction of the initial parameters of the wire manufacturing mode and increase of the ratio between the width and the thickness of the tape by more than 15 is impractical, as this reduces the productivity of the process and worsens the quality of the manufactured wire.

Example 3. The width of the tape used is 12 mm, the thickness is 1.0 mm, with a ratio of these dimensions of 12. During the formation of the blank, the edge of the tape is bent at an angle of 137" for each bending stage, and the vertical axis of the elliptical cross-section exceeded the size of the horizontal one by 1.1 times. in the first stage of the first stage of drawing, the workpiece was crimped to 1695. The pulling force was equal to 0.7t. During the formation of the workpiece to its final diameter, no twisting of the wire was observed. The drawing is also satisfactory, no wire breaks were recorded during the entire technological cycle.

As can be seen from the above results, the compliance of the parameters of the mode of implementation of the method chosen in the declared range of values is the most rational from the point of view of productivity and profitability of the process. Such a combination provides good technological indicators of the wire manufacturing process, even in the case of 10095 filling the shell with a powder filler. sposo Ko fig. 1 Fig. 2nd as sao

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Claims (2)

1. The method of manufacturing powdered wire, during which the dimensions of the cross section of the rising belt are calculated in advance, a chute is formed from the moving belt, it is filled with a powder charge during movement, the chute is closed to form a tubular blank, and the billet is drawn repeatedly to the required diameter of two stage, which differs from that the dimensions of the cross-section of the tape are chosen from the ratio of width to thickness in the limits of 8-15, the formation of the trough is performed by repeatedly bending the edges of the tape at an angle of 10-15 degrees for each bending, the tubular blank in the cross-section is given the shape of an ellipse, the vertical axis of which is formed in 1 .05-1.15 times longer than its horizontal axis, the first drawing pass at the first stage is performed with a single crimp 13-1995. 2. The manufacturing method according to claim 1, which is characterized by the fact that before the beginning of the drawing of the tubular workpiece, which has the shape of an ellipse, the closed edges of the tape are heated to the melting temperature of the edges and then the ellipse is deformed into a circle with the formation of a thermomechanical welded joint in the zone of closing the edges of the tape .