JPS63132798A - Continuous production of flux-cored wire - Google Patents

Abstract

PURPOSE:To assure the pipe diameter necessary for flux supply and to smooth the flux supply by adopting an inclination system and incorporating a rolling stage having the large capacity to reduce the pipe diameter in a line, thereby increasing the diameter of an open seam pipe. CONSTITUTION:Respective devices from a forming device 3 to a reducing mill 6 are inclinedly disposed. The stands of the respective devices are vertically ascendable and descendable around the fulcrum points on the down stream side and can incline to desired angles. The angle of the inclination thereof is larger than the angle of repose of the flux to be introduced into the pipe. The welded pipe is passed through the calibers formed of the plural rolls of the mill 6 and is thereby rolled to the set pipe diameter. The flux is deposited in the position of the rolled pipe where the required flux filling rate is obtd. in said rolling stage. The roll rotating speeds of the multi-stage rolling mill are adjusted according to the bulk density of the flux to adjust the rolling tension between the rolling stages, by which the thickness of the pipe is controlled and the required ratio between the thickness and the outside diameter is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to the manufacture of flux-cored wires suitable for use in automatic or semi-automatic arc welding, particularly flux-cored wires in which the longitudinal joints of the sheath are welded. It is about the method.

(Prior art) In general, the technology for manufacturing flux-cored wire by electric resistance welding is to continuously form a metal strip into a U-section and an OwfI surface to form a tubular body (open seam tube), and in this forming process, After filling the inside of the open seam tube with a flux containing desired components such as metal powder and deoxidizing agent, we butt weld the opposing longitudinal sections of the open seam tube to produce a flux-cored welded tube. It is known to produce flux-cored wire by sending the wire to a wire drawing process. When filling flux, a technique is also known in which the open seam tube is filled with an angle of repose greater than or equal to the angle of repose of the flux.

High frequency induction resistance welding, high frequency contact resistance welding, low frequency butt welding, etc. are used for butt welding of the L oven seam tube. For this reason, there is a problem in that the magnetic material contained in the flux is attracted to both parts of the pipe to be welded by the induced magnetic field generated by the current in the welding part, and becomes entangled in the welding part, making it impossible to obtain a normal welded part. There is also the problem that the flux changes in quality due to the welding heat, impairing its properties as a welding material.

Therefore, in order to solve this problem, conventionally, the tip of the supply pipe for supplying flux into the pipe was positioned downstream of the welding point of the open seam pipe with the welded part tilted. The flux is supplied to prevent the flux from being adsorbed directly to the edge of the pipe being welded. (For example, JP-A-58-449
(Refer to 93.61-56794 and 60-68193) (Problems to be Solved by the Invention) However, the above conventional method has the following problems.

The size of the flux supply pipe determines the amount of flux supplied, and if an attempt is made to increase the supply amount, the size of the supply pipe will inevitably increase. However, the size of the supply pipe is limited by the size of the forming pipe, and there is a limit to the amount of flux supplied, and this limit value impedes productivity. On the other hand, if the forming tube size is increased in accordance with the supply tube size, the wall thickness of the forming tube must be increased in order to maintain the desired flux filling rate, which increases the load on the subsequent rolling process. This makes it necessary to increase the number of rolling mill stages, which is not economically advisable.

The present invention solves these problems with the conventional method, allows the pipe diameter before welding to be made as large as possible, allows a wide adjustment range for flux supply amount, and prevents flux from being adsorbed at the welding part. Another object of the present invention is to provide a method for manufacturing a flux-cored wire in which the flux filling rate can be controlled.

(Means and operations for solving the problems) The structure of the present invention to achieve the above object is as follows. That is, a metal strip is continuously formed into a tubular body, and during this forming process, a desired flux is supplied into the inclined tubular body through a flux supply pipe whose tip is located downstream of the welding point, and In the continuous manufacturing method of flux-cored wire, which involves welding opposing parts of the body against each other to form a welded tube, at least the angle of repose between the welding point and the flux deposition point is larger than the angle of repose of the introduced flux. A multi-stage rolling mill is installed to tilt the welded pipe at an angle and subsequently roll the welded pipe to a required diameter, and the tension between the rolling rolls is adjusted to change the ratio of the wall thickness to the outer diameter of the rolled pipe. A continuous manufacturing method for black-cored wire, characterized in that the flux filling rate is controlled by

As a result, in the present invention, it is easy to fill the flux due to the inclined method, and since the flux passes through the supply pipe at the welding point, the flux is not attracted to both edges of the pipe to be welded by the induced magnetic field. In addition, since rolling, which has a large capacity to reduce the tube diameter, is directly connected, the tube diameter can be increased in the forming stage, and accordingly, the diameter of the flux supply tube can also be increased. Furthermore, multi-stage rolling allows the tension between the roll stages to be adjusted, making it possible to adjust the ratio of the wall thickness and outer diameter of the rolled tube to match the bulk density of the flux, making it easy to control the desired flux filling rate. be able to.

The present invention will be described in detail below with reference to the drawings.

Fig. 1 shows a simplified example of equipment arrangement for explaining the method of the present invention. 3 is a forming device for forming the band plate 2 into U and O shapes in cross section; 4 is a tubular body 2A formed in the middle of the forming device 3 (the cross section is approximately 0 shape); 5 is a flux supply device for supplying a flux of a desired component through a supply chute 9 into an open seam tube (hereinafter referred to as an open seam tube because the opposing edges have not yet been welded); 5 is an open seam supplied with flux; A welder 6 butt-welds the opposing longitudinal edges of the pipe, a rolling machine 6 reduces the welded pipe 2B to a desired diameter, and a light rolling machine 7 applies light rolling to the flux-filled rolled pipe 2C. A straightening machine for straightening, 8 indicates a coil wound up after rolling. These devices are arranged in direct connection and each process is performed continuously without interruption.

Therefore, in the illustrated example, each device from the T & type device 3 to the reducing mill 6 is arranged at an angle. That is, for example, each of the devices in this range is configured such that the pedestal that holds them can be raised and lowered in the vertical direction about a fulcrum on the downstream side, and can be tilted at any angle. This angle of inclination may be greater than the angle of repose of the introduced flux.

The forming device 3 is of a type that includes a group of known forming rolls that are used to form a strip into a circular cross-sectional shape when manufacturing ordinary electric resistance welded steel pipes. Also, flux supply equipment! ! ! Reference numeral 4 is provided with a hopper for accommodating flux adjusted to a desired composition and a supply amount adjustment mechanism for feeding the required amount to the supply pipe 9. Furthermore, the welding machine 5
For example, as shown in FIG. 3, this is a known type having a high frequency coil 1O and a squeeze roll 11, and butt-welding the opposing edges of continuously fed open seam tubes 2A. Note that necessary devices such as an external beat counter 12 are provided at the rear of the welding machine.

In addition, the rolling mill 6 installed after welding Ia5 accurately reduces the welded pipe 2B to the desired pipe diameter and wall thickness.
It is equipped with multiple stages of rolling rolls, and this is also a well-known 20
-L or 30-L type is adopted. The straightening device 7 arranged between the rolling mill and the winding machine
It has the function of C straightening and light rolling.

The flux supply pipe 9 is inserted into the oven seam pipe 2A at an appropriate position during the forming stage as shown in FIG. It is also necessary to place it on the downstream side. The diameter of the supply pipe 9 may be sufficient as long as it can supply the expected maximum supply amount of flux.

The material of the supply pipe must be non-magnetic, such as ceramics or plastics, at least in the vicinity of the welding point, in order to avoid the generation of an induced current due to the welding current. In addition, it is better to use a flexible plastic material for the upstream side of the supply pipe, especially the bent part, so that it can be attached to the supply pipe after adjusting the rolls of the molding machine to the specified position, making it easier to handle the equipment. becomes easier.

If part of the supply pipe is not made flexible, all molding machine rolls upstream of the supply pipe insertion position must be opened and the supply pipe inserted, and then the molding machine rolls must be adjusted. Since roll adjustment is required each time the tube is replaced, handling of the device becomes more frequent.

The actual manufacturing process of flux-cored wire using the above-mentioned equipment will be explained below in accordance with the present invention.

The strip 2 unwound from the coil 1 is fed through a looping device (not shown) to a forming device 3 disposed obliquely, where it is bent into U and O shapes in cross section to form an open seam tube 2A. A flux supply tube 9 is inserted into the oven seam tube 2A at an appropriate position in the molding device 3 through the opening of the tube. When supplying this flux, in the present invention, the tip of the flux supply pipe 9 is located on the downstream side beyond the welding machine 5, and the flux F from the tip of the supply pipe 9 is inclined at an angle greater than the angle of repose of the flux. It slides down inside the welded pipe 2B and accumulates.

The open seam tube bent into a circular cross section by forming rolls reaches the position of the welding machine 5, and is connected to, for example, a high frequency coil 10.
The opposite edges are abutted against each other and pressed together by the squeeze roll II. In addition, as a welding method, any of high frequency induction resistance welding, high frequency contact resistance welding, or low frequency butt seam welding may be adopted.
Further, during welding, since a flux supply pipe is present within the pipe, it is preferable not to use an impeder used in normal electric resistance welding. After welding, the outer bead is scraped off with a cutter 12, and then sent to the next rolling process.

In the rolling mill 6, the welded pipe 2B is
In the present invention, flux is deposited at the position of the rolled tube 2C where the required flux filling rate can be obtained in this rolling process. It is something.

The filling rate of the flux is uniquely determined by the ratio t/D between the wall thickness t and the outer diameter of the rolled tube at the position where the flux is deposited, and the bulk density of the deposited flux.

However, the bulk density of flux changes depending on the type of flux, and even when producing a large amount of one type of flux, it is necessary to control t/D in order to obtain the desired flux filling rate. In the present invention, the rolling tension between the roll stages is adjusted by adjusting the roll rotation speed of the multi-stage rolling mill according to the bulk density of the flux, and the wall thickness t of the tube is controlled to obtain the required t/D. It is characterized by obtaining. Note that the outer diameter of the tube is determined by the roll hole type of the rolling mill and cannot be changed during operation.

Incidentally, the relationship between the bulk density of the flux, the t/D of the tube, and the flux filling rate f is shown in FIG. That is, according to experiments, if the bulk density of the flux designed with a flux filling rate of 15% is 2.00 g/cm', then in Figure 6, the part with the flux bulk density of 2.00 g/cm' Proceed to the right and go down to the intersection with the 15% flux filling rate line to find the required pipe wall thickness ratio t/D, which is 0.177.Similarly, the bulk density of the flux to be filled is 1.80
g/cm", the pipe wall thickness ratio t/D is 0.168. Even for a flux designed with a filling rate of 20%, if the bulk density is 2.00 g/c+a", t/D is 0.168. 1
If a pipe wall thickness ratio of 47 is selected, a wire with a filling rate of 202 can be manufactured.

In addition, according to the research of the present inventors, the material of the welded pipe is 0.0
5$ C-0, 4$llIn -0, 1$Si -0,
A hot-rolled coil of 015$P -0,013$S and a welded pipe with a wall thickness of 2.0mm and an outer diameter of 20m were prepared using 20-1 method 1.
When rolled using a 0-high rolling mill with tension generated in each stand, the finished size is as shown in Figure 7, the outer diameter is the same as 12.7 mm, but the wall thickness increases as the tension increases. It is decreasing according to Therefore, when the density of the filling flux is low, t/D is reduced by applying a large tension between the rolls, and conversely, when the density of the flux is high, t/D is increased by rolling without applying any tension. Therefore, according to the present invention, a flux-cored wire with a constant flux filling rate can be manufactured.

The tendency of this change in t/D is also influenced by the pipe material, roll diameter, roll shape and number of rolls, rolling speed, etc., but by setting each of these in advance, the t/D at which flux should be filled can be adjusted as described above. It is requested as expected. That is, for any flux, by measuring the bulk density of the flux, the t/D of the pipe to be filled with flux is determined to be the 6th
This can be determined from the figure, and the outer diameter of the pipe that corresponds to this t/D can be easily determined from FIG. In the present invention, the t/D of the tube that provides the desired flux filling rate is obtained in this manner, and control is performed so that the flux deposition surface is always located at this position.

Therefore, in order to control the flux deposition surface to a predetermined position, it is necessary to detect the position of the flux deposition surface inside the tube from outside the tube. As an example of a method for detecting the flux deposition level, a flux level meter 13 equipped with a magnetizing coil and a detection coil as shown in FIG. 4 can be used. As shown in Figure 1, this is installed at the position of the tube with t/D where the desired flux filling rate can be obtained.In an actual production line, tension is applied to the electrode tube with the desired t/D at the detector position. (rolling), there is always flux deposited on the surface.

Adjust so that it is near the level detector 13. In other words, when there is a 7 lux deposition surface above the level detector, the
By decreasing the supply amount of flux and increasing the supply amount when there is a flux deposition surface below the level detector (it is also possible to control the pipe forming speed by keeping the flux supply amount constant), The main feature of the flux supply control method of the present invention is that the flux deposition surface is always controlled so that the t/D of the tube remains within the same range. , the flux deposition surface is t
If /D is controlled within the same range, the flux filling rate is always constant, so there is an advantage that a flux-cored wire of good quality can be easily manufactured. In other words, when the final roll of the rolling mill shown in FIG. 1 is rolling a tube of t/D with a desired filling rate, the flux deposition surface may be located at any position from A to B below the final rolling roll. When it goes above the rolling rolls, t/D becomes small for the first time, so the filling rate becomes high, and below B, the inside of the pipe is no longer filled, so the filling rate becomes low, but if it is within the range of A to B. Since the filling rate is completely uniform, the range of flux deposition surface positions is wide, and control can be performed extremely easily.

The rolled tube 2C filled with flux through the rolling process is
After passing through the straightening machine, it is wound up into a coil 8 by a winding machine. In addition, if necessary, light rolling (3 to 100 oz.
It is desirable that the flux be filled and deposited in a natural state to move during subsequent steps. Note that this straightening machine may be omitted in equipment that brings the flux deposited surface in the middle of rolling.

The wound coil is sent to a separate annealing process and/or die wire drawing process to obtain the desired final diameter, or it is made into a product through a cleaning process and a plating process after the wire drawing process. 0 In the present invention, these subsequent steps can be continuously connected to the rear part of the rolling step and configured as a penetrating line.

(Effects of the Invention) As explained above, according to the method of the present invention, the following effects can be expected.

■In addition to adopting an inclined method, we have incorporated a rolling process in the line that has a large capacity to reduce the tube diameter, making it possible to increase the diameter of the open seam tube, ensuring the tube diameter necessary for flux supply, and reducing flux. This has the advantage of smooth supply and wide range of supply amount adjustment.

(2) By adjusting the tension between rolling rolls, the t/D of the rolling tube can be adjusted to obtain a desired flux filling rate, so that a flux with a uniform filling rate can be easily obtained for any type of flux.

■Also, since flux fills the pipe, post-process
For example, during annealing, pickling, plating, wire drawing, etc., flux does not move inside the pipe, resulting in defective welds,
Flux deterioration and flux particle size and component segregation are prevented, and a welding wire of excellent quality can be obtained.

(Example) As shown in Fig. 1, the forming machine, welding machine, and rolling machine are tilted at an angle of 70", and a flux with an angle of repose of 32 to 48 degrees is applied from the flux supply device 4 to the tip of a Teflon (trade name) tube. It was supplied through a supply pipe 9 connected with glass.The size of the metal strip was 2.0L x 64'.

Component is 0.06X C-0,1XSi -0,5$11
Using extremely mild steel hot rolled material of n -0,010 I did it.

At this time, rolling was carried out from 21 mm to 12.0 mm using 6 stands of a 30-mill system. Table 1 shows the results of the rolling condition settings, the t/D (D: 12.0 mm) of the tube after rolling, and the actual flux filling rate. Incidentally, the amount of flux supplied was determined by installing a flux level meter below the final rolling roll.

For test Nos. 1 to 7, the desired flux filling rate was obtained by adjusting the inter-stand tension of the rolled pipe to the t/D of the pipe corresponding to the flux bulk density.

[Brief explanation of the drawing]

FIG. 1 is an overall schematic diagram showing an example of manufacturing equipment for explaining the method of the present invention, and FIGS. 2, 3, and 4. and Figure 5 is an enlarged detailed view of Figure 1 at the ■■■■ position, Figure 6 is a graph showing the relationship between flux bulk density, tube t/D, and flux filling rate, and Figure 7 is a graph showing the relationship between tube wall thickness and It is a graph showing the relationship between roll tensions. l...Metal strip coil, 2-...Metal strip, 2^...
・Open seam pipe, 2T・・Welded pipe, 2G・・Rolled pipe, 3・Forming device, 4・Flux supply device,
5...Welding machine. 6... Rolling machine, 7... Straightening machine, 8... Coil, 9
-...Chute, 10-...High frequency coil, 11-...
・Squeeze roll, 12...Beat cutter, 13-・
-Level detector, 14-... Pipe-making speed detector.

Claims (1)

[Claims] A metal strip is continuously formed into a tubular body, and during this forming process, the metal strip is inserted into the tubular body, and the tip thereof is passed through a flux supply pipe located downstream of the welding point. A method for continuously producing a flux-cored wire, which comprises supplying a desired flux into a tubular body in an inclined state, and welding opposite edges of the tubular body against each other to form a welded tube, at least at the welding point and flux deposition. The points between the points are inclined at an angle larger than the angle of repose of the flux to be introduced, and a multi-high rolling mill is installed to continuously roll the welded pipe to the required diameter, and the tension between each roll stage of the rolling mill is A method for continuously manufacturing a flux-cored wire, characterized in that the flux filling rate is controlled by adjusting and changing the wall thickness and outer diameter ratio of the rolled tube.