JPH04231111A - Method and device for treating surface treated steel sheet for steel tube - Google Patents

Abstract

PURPOSE:To prolong the life of cutting tool with which bead after welding is machined by removing a plated layer of a certain width of a surface treated steel sheet for steel tube with a plated layer by projecting grinding particles to both end parts in the width direction in running. CONSTITUTION:A grit supply pipe 5 of which one end is attached to a grit separating, recovering and supplying device 4 or an air feeding pipe 6 together with this supply pipe 5 are introduced into a chamber 1 with slits 10 on its side walls. Plural grit projecting nozzles 3 which are connected to the grit supply pipe 5 or this pipe and the air feeding pipe 6 are faced to one side or top and bottom sides of the steel sheet S and provided by arranging in parallel in the position of both width end parts of the steel sheet. Further, a grit recovery tank 7 is provided in the lower part of the chamber and the recovery tank 7 and the grit separating and recovering device 4 are connected with a connecting pipe 8. Then, the life of cutting tool with which bead after welding is machined can be prolonged by removing the plated layer at the width ends of the steel sheet before tube-making and a high-quality steel tube can be manufactured.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is a surface-treated steel sheet for steel pipes (
The present invention relates to a method and apparatus for treating a surface-treated steel sheet for steel pipes, which treats both ends in the width direction that become welded parts of a steel pipe, and in particular enables efficient cutting of weld beads in the manufacture of electric resistance welded steel pipes.

0002

2. Description of the Related Art Electric resistance welded steel pipes are normally manufactured in a manufacturing equipment line as shown in FIG. That is, the uncoiler 101
The steel plate (strip) S unwound from the coil is connected to the previous steel plate (strip) S using the shear/welder 102, and after straightening the steel plate S using the leveler 103, the edge scuffer 1
After cutting the end face with 04, pipe making mill 105
The pipe is formed into an open pipe using a welding device 106, and then the edges of the pipe are seam welded using a welding device 106 to form a steel pipe. after that,
Both the inner and outer surfaces of the weld bead formed on the steel pipe are cut with a cutting tool 107, and the pipe diameter is further reduced with a sizing mill 108, and then the pipe is cut to a predetermined length with a press cutter 109 and shipped. In the figure, 110 is a looper for retaining the steel plate, and 111 is a leveler provided as necessary to straighten the steel pipe.

[0003] When this electric resistance welded steel pipe is to be used in a strongly corrosive environment, it is manufactured from a steel plate that has been surface-treated by plating or the like. However, when such a surface-treated steel sheet is used, a major problem arises in manufacturing.

That is, in the above step, when the weld bead after pipe making is cut with a cutting tool, the plated metal is deposited on the cutting edge of the cutting tool, and the amount of welding gradually increases to change the constructed cutting edge (rake angle). Cutting ability will be significantly reduced. This causes deterioration of the quality of the steel pipe, and in order to maintain the quality, the line must be stopped frequently to replace the bits, resulting in a decrease in productivity and an increase in manufacturing costs. bring.

There is also a grinding process using a grinder without using a cutting tool, but since the abrasive grains on the surface are significantly clogged with plated metal, it is necessary to replace them frequently like the cutting tool, or to use special means such as online dressing. It becomes necessary.

[0006] As a method for removing the plating layer of a Zn-plated steel sheet, Japanese Patent Laid-Open No. 63-96224 proposes shot blasting. However, this method deals with processing scraps of Zn-plated steel sheets, and moreover, the scraps are heated to a high temperature of 700 to 900° C. and then shot blasted. Therefore, it cannot be used for processing high-quality products.

[0007]

[Problems to be Solved by the Invention] The present invention aims to remove the plating layer of a specific portion of a surface-treated steel plate, such as plating, during running, and in particular, to remove the plating layer from both ends of the surface-treated steel plate before welding in the manufacturing process of ERW steel pipes. Provided is a method and device for processing surface-treated steel sheets for steel pipes, which aims to extend the life of a cutting tool for bead cutting after welding by removing the surface layer over a certain width, and to obtain high-quality steel pipes. The purpose is to

[0008]

[Means for Solving the Problems] In order to achieve the above object, the present invention has the following configuration. That is, in the treatment of surface-treated steel sheets for steel pipes, (1) a surface-treated steel sheet for steel pipes having a plating layer is continuously run, and during the run, abrasive particles are projected on both ends of the steel plate in the width direction to form a fixed width. (2) In the ERW steel pipe manufacturing line, abrasive particles are projected onto both ends in the width direction of a surface-treated steel sheet for steel pipes having a plating layer that runs continuously at a position before the pipe-making equipment. and (3) a treatment method in which both ends in the width direction of the steel plate in each of the preceding items are treated with abrasive particles, and then the treated portion is further cut or ground, Furthermore, (4) grind particles (grid) at one end in a chamber with steel plate passing holes in the side wall.
A grid supply pipe attached to the separation and recovery device and an air supply pipe if necessary are introduced, and a plurality of grid projection nozzles connected to the grid supply pipe or the air supply pipe together with the grid supply pipe are connected to one side of the steel plate. Alternatively, they are installed vertically facing each other and arranged in parallel at both width ends of the steel plate, and furthermore, a grid collection tank is provided at the bottom of the chamber, and the collection tank and the grid separation and collection device are connected through a connecting pipe. Or furthermore,
(5) A processing device for surface-treated steel sheets for steel pipes, characterized in that the grid projection nozzles, which are arranged in parallel at both width ends of the steel sheet, are installed movably according to the width of the traveling steel sheet. be.

[0009]

[Operation] The present invention will be explained in detail below. During the manufacturing process of electric resistance welded steel pipes, excess build-up occurs in the weld bead formed by high-frequency welding and pressure joining, so this is removed using a cutting tool installed after the weld and the bead shape is shaped. When an electric resistance welded steel pipe is manufactured using a surface-treated steel plate such as Zn plating or Al plating, the plated metal adheres to the weld bead. As mentioned above, plated metals are generally soft and tend to weld to the cutting edge of the cutting tool during bead cutting, reducing the cutting ability.

[0010] In the present invention, while traveling on the surface-treated steel plate, grids (grinding particles) are projected onto both ends in the width direction of the steel plate that will become the welding part at a position before the pipe making equipment in the ERW steel pipe manufacturing process. A predetermined width of the plating layer is removed to prevent the plating metal from adhering to the weld bead.

FIG. 1 shows an example of an apparatus for removing a steel plate plating layer in which the method of the present invention is carried out.
A steel plate (hoop) S is passed between a grid injection device provided inside the steel plate, and plating layer removal portions 2 are provided at a predetermined width at both ends of the steel plate. For example, when processing a single-sided plated steel plate, the grid injection device has a plurality of grid injection nozzles 3 arranged in parallel in the steel plate traveling direction on at least one side of the steel plate at both width ends of the steel plate, and is used for, for example, double-sided plating. In such cases, they are arranged vertically facing each other. In this way, the grid injection nozzles 3 can be arranged vertically on either one side or on both sides (opposed) as necessary, and even if they are installed vertically, the operation of one or both sides can be controlled. The selection can be made by opening or closing a valve (not shown) provided within the system. The injection nozzle 3 is connected to a grid supply pipe 5 whose one end is connected to the grid separation, recovery and supply device 4, and is connected directly or via an appropriate support means with an air supply pipe 6 for supplying pressurized air. There is. The grid is conveyed using a fluid such as air or water as a medium, and if these media are used under pressure, the air supply pipe 6 may be omitted. Reference numeral 7 denotes a grid recovery device provided at the bottom of the chamber 1, and is connected to the separation and recovery device 4 through a transport connecting pipe 8. Reference numeral 9 denotes a width adjustment device, which adjusts the position of the injection nozzle 3 according to the width dimension of the steel plate. Reference numeral 10 denotes a slit provided in the side wall of the chamber 1, which serves as a passage for the steel plate.

In the above-mentioned apparatus, the width interval of the injection nozzles 3 is adjusted according to the width of the surface-treated steel plate to be traveled and treated, and the grid selectively separated by the separation and recovery device 4 is supplied to the injection nozzles 3 through the supply pipe 5. If necessary, at the same time, pressurized air sent from the air supply pipe 6 is used to spray the grid from a nozzle, so that both ends of the steel plate to be welded have a certain width (one width 10
It is preferably less than mm. ) to polish away the plating layer in this area. The grid ejected from the nozzle has a fairly high velocity, which causes wear on the nozzle tip. Therefore, at least the nozzle tip is made of alumina, SiC,
It is preferable to use a wear-resistant material such as Sialon.

[0013] The grid projected onto the steel plate from the nozzle is
After grinding, the particles are collected in a collection tank 7 through a chute at the bottom of the chamber, and from there, they are transported to a grid separation and collection device through a transport connecting pipe 8. The grid separation and recovery device separates the reusable grid from other ground plated metal and dust, and only the former is reused. In addition, a fluid such as air or water is used to transport the grid from the recovery tank to the separation and recovery device.

The grid (particles) used for grinding is preferably made of materials such as, but not limited to, SiC, alumina, and glass beads. In addition, the particle size greatly affects equipment and operations. Figure 2 shows the grid particle size (mm
), grinding amount (hr, solid line) and injection nozzle life (mg
/cm2 ・sec, dotted line).
As the grid particle size increases, the amount of grinding increases, but the life of the nozzle decreases. It goes without saying that the longer the nozzle life, the better, but at least the regular inspection period (7
20 hours), and the amount of grinding should be larger from the viewpoint of equipment cost, and on the other hand, from the viewpoint of line operation, it is necessary to set it to at least 1 mg/cm2.sec. For this reason, it is preferable to set the grid particle size to 20 μm or more and 2 mm or less.

Air, water, or the like is used as the grid conveyance medium to the nozzle, and the spray from the nozzle is performed using pressurized air. This air pressure has a large effect on the amount of grinding and the equipment cost. Figure 3 shows these relationships (the solid line shows the amount of grinding and the dotted line shows the equipment cost).Increasing the air pressure increases the grinding force and increases the amount of grinding, but the amount of nozzle wear increases and the service life is shortened. Air pressure is 15.
The amount of grinding is preferably at most 0.5 kg/cm2 since the amount of grinding is required to be at least 1 mg/cm2. In the present invention, plated metal on the surface of a steel plate can be removed by projecting abrasive particles as described above. A combination of cutting or grinding using a grinder or the like may be performed. In these combined machining operations, most of the plated metal is removed by the projection of abrasive particles, so the tool life is not reduced.

[0016]

[Examples] Examples of the present invention will be described below. In the electric resistance welded pipe production line shown in Fig. 4, the plating layer removal device shown in Fig. 1 is installed before the pipe-making mill, and the plating layer at the width end of the aluminum-plated steel plate is removed as the pipe-making material, and then the plating layer is removed. After seam welding, the bead portion was cut and shaped using a cutting tool. The test conditions on the production line are as follows. Line speed 100mm/min Steel plate size Width 100mm x thickness 1.25mm Plating thickness 25mm (single side) Plating layer removal width 3m
m (one side) In order to remove this plating layer, the conditions for grinding and projecting the particles were as follows. Conveying air pressure to nozzle 5 kg/cm2 Grid type SiC grid diameter
500-800μm nozzle distance
Air (dry) or water (wet) was used as the transport medium for the 30 mm grid. The test results are shown in Table 1.

[0017]

[Table 1]

It can be seen from the results in Table 1 that the cutting tool life of the steel pipe inner bead is about 10 minutes when the steel plate plating layer is not removed in the conventional method (Test No. 13), but it When this was done, it was 8 to 33 times that amount, making it possible to significantly extend the lifespan.

[0019]

[Effects of the Invention] As described above, the present invention can be used to manufacture steel pipes from surface-treated steel sheets, especially in the ERW steel pipe manufacturing line, by removing the plating layer at the width end of the steel sheet, which will be the welded part, before pipe manufacturing. This makes it possible to significantly extend the life of the cutting tool used to shape the bead after welding, making it possible to manufacture high-quality steel pipes with excellent bead shapes with high productivity.

[Brief explanation of the drawing]

FIG. 1 shows an example of an apparatus for removing a steel plate plating layer according to the present invention.

FIG. 2 shows the relationship between the grid particle size (mm), the amount of grinding (solid line), and the life of the injection nozzle (dotted line).

FIG. 3 shows the relationship between air pressure, grinding amount, and equipment cost.

FIG. 4 is a diagram showing an example of an ERW steel pipe manufacturing line.

[Explanation of symbols]

1: Chamber 2: Plating removal part 3: Grid injection nozzle 4: Grid separation and collection device 5: Grid supply pipe 6: Air supply pipe 7: Grid collection device 8: Transport connecting pipe 9: Width adjustment device 10: Slit

Claims (5)

[Claims] 1. A surface-treated steel plate for steel pipes having a plating layer is continuously run, and during the run, abrasive particles are projected onto both ends of the steel plate in the width direction to remove a certain width of the plating layer. A method for treating surface-treated steel sheets for steel pipes. 2. In an electric resistance welded steel pipe production line, grinding particles are projected onto both ends in the width direction of a surface-treated steel sheet for steel pipes having a plating layer that runs continuously at a position before the pipe-making equipment to form a constant width. A method for treating a surface-treated steel sheet for steel pipes, the method comprising removing a plating layer. 3. The steel pipe according to claim 1 or 2, wherein after treating both ends in the width direction of the surface-treated steel plate for steel pipes according to each of the preceding items with grinding particles, the treated portions are further subjected to cutting or grinding processing. Treatment method for surface-treated steel sheets. 4. A grid supply pipe having one end attached to a grinding particle (grid) separation, collection and supply device, or an air supply pipe together with the supply pipe is introduced into a chamber having a steel plate passage hole in the side wall, and the grid supply pipe is connected to the grid supply pipe. Alternatively, a plurality of grid projection nozzles connected to this and an air supply pipe are installed on one side of the steel plate or vertically opposed to each other, and are arranged in parallel at both width ends of the steel plate, and further installed in the lower part of the chamber. A processing device for surface-treated steel sheets for steel pipes, characterized in that a grid recovery tank is provided in the grid recovery tank, and the grid separation and recovery device is connected to the grid recovery tank through a connecting pipe. 5. The steel pipe surface according to claim 4, wherein the grid projection nozzles are arranged in parallel at both width ends of the steel plate and are movably installed in accordance with the width of the traveling steel plate. Processing equipment for processed steel plates.