JP4862429B2 - Steel pipe inner surface printing method - Google Patents

Description

  The present invention forms a steel strip into a cylindrical shape and welds the attached steel strip width direction both ends to manufacture a welded steel pipe (for example, an electric resistance welded steel pipe). The present invention relates to a method for printing on the surface of a steel strip that becomes the inner surface of a steel pipe after forming.

  In general, an electric resistance steel pipe is formed by forming a cylindrical shape with a group of forming rolls while rewinding a steel strip wound in a coil shape (hereinafter simply referred to as a coil) with an uncoiler and continuously running the steel strip. It is manufactured by electrical resistance welding at both ends in the width direction of the steel strip. That is, for the production, for example, a steel slab obtained by continuously casting molten steel is heated to a predetermined temperature (usually 1200 to 1300 ° C.) in a heating furnace, and then rolled up to a predetermined dimension by hot rolling. A coil is used. Then, as shown in FIG. 4, the coil 1 is rewound by the uncoiler 2, smoothed by the leveler 3, and both ends in the width direction are adjusted by the edge mirror 4, and then rolls having various shapes are arranged in multiple stages. The steel strip surface is leveled into the group of forming rolls 5 and fed at a constant speed. The cylindrical body processed by the forming roll 5 is continuously heated by the induction heating device 6 at both ends in the width direction, pressed by the squeeze roll 7, and subjected to electric resistance welding. 8 (hereinafter referred to as “element tube 8”). The bead formed in the joint portion (seam portion) extending in the longitudinal direction of the raw tube 8 is removed by the bead cutting means 9. Further, the raw tube 8 is cut to a certain length by a running cutter 10 and the dimensions are adjusted by a drawing mill. And after inspecting whether it has a desired dimension and a characteristic, it becomes an ERW steel pipe as a primary product. The coil 1 is divided into small pieces (slits) in the width direction of the steel strip or cut in the longitudinal direction according to the user's demand, that is, the size and amount of the ERW steel pipe to be manufactured. The coil (referred to as a “skelp”) 1 is often used after being used.

  Such an electric resistance welded steel pipe 13 has a use as a material for manufacturing parts such as suspension pipes and exhaust gas pipes of a “vehicle” such as an automobile. These parts are cut into shorter lengths (0.5 to 2 m) of the ERW steel pipes of the above-mentioned fixed length (fixed length: 6 m) and then subjected to secondary processing such as bending and partial enlargement. And finally built into the vehicle.

  By the way, when a vehicle such as an automobile has some trouble after being released, it may be a situation where a car incorporating the same kind of problem part is collected in order to replace the part. is there. This recovery is labor intensive, time consuming and expensive, so it is desirable to incorporate defect-free parts and avoid recovery as much as possible. It is also important to find out the cause of the trouble from the viewpoint of safety and prevention of recurrence. In that case, the defective part is removed from the collected automobile, and the material history of the defective part is asked.

  Conventionally, this material history is attached to a bundle of steel pipes to be shipped (a collection of dozens of steel pipes) with a tag that describes the factory, date of manufacture, and order number (control number for each manufacturing month). I managed it. Therefore, there is a problem that the material of the defective part can be identified only by at least several coils 1 (about 100 tons in weight). In other words, since the number of secondary processed parts manufactured from one coil is enormous, the number of automobiles that must be collected is also very large. In addition, the manufacturing history may be printed on the outer surface of each steel pipe, but in practice, the steel pipe is used after being coated on the outer surface, so the printing cannot be read.

  On the other hand, Patent Document 1 discloses a manufacturing history management method of a steel pipe that can pursue the material history of each of secondary processed parts made of steel pipe as a raw material or individual steel pipe before shipment. .

  That is, as shown in FIG. 2, the manufacturing information of the steel strip 17 is printed on the surface of the steel strip 17 before being formed into a cylindrical shape after forming, as shown in FIG. . At that time, the printing position is within the range of the length of the secondary processed part manufactured by further cutting the steel pipe 13 having a certain length obtained in the manufacturing process, that is, the range of the length of the secondary processed part. I'm trying to do it at the pitch.

  The printed contents are alphanumeric characters representing the date of manufacture, the skelp number of the steel strip used, and the skelp position (distance from the tip of the skelp). As an example, as shown in FIG. 3, it is “05 1109 1215 AB 0721”. This means November 9, 2005, 12:15, skelp number (AB), distance 721m from the skelp tip.

  By performing such printing, if a trouble (during machining or after incorporation) occurs in the secondary processed part 16, it can be disassembled and the material history can be identified for each secondary processed part.

On the other hand, in the manufacturing process of the electric resistance welded steel pipe, the raw pipe obtained by forming and welding the steel strip is heated, and in the warm region (500 to 900 ° C.), a high diameter reduction ratio (for example, 50 %) Has been proposed (see, for example, Patent Document 2), which produces a high-performance ERW steel pipe having both high strength and high workability.
JP 2005-131646 A JP 2000-144329 A

  As described in Patent Document 1, a method of printing manufacturing information of the steel strip with alphanumeric characters on the surface of the steel strip that becomes the inner surface of the steel pipe after forming is described in Patent Document 2. High strength and high workability are achieved by heating the blank obtained by forming and welding the band and performing high-reduction rolling (for example, 50% reduction) in the warm region (500 to 900 ° C.). When applied to a method for manufacturing a high-performance electric resistance welded steel pipe having both properties, the following problems arise.

  That is, the alphanumeric characters printed on the surface of the steel strip are stretched and deformed in the tube length direction by the subsequent high-diameter rolling, and when the steel tube is disassembled at a later date, the manufacturing information of the corresponding steel strip is read. It becomes difficult. Further, when the heating temperature of the raw tube is high (for example, 1000 ° C.), the ink may be oxidized and the printing may become unclear.

  The present invention has been made in view of the circumstances as described above, and in the manufacturing process of an electric resistance welded steel pipe or the like, on the steel strip surface that becomes the steel pipe inner surface side after forming, when printing the production information of the steel strip, Even when the formed tube is heated and subjected to high-reduction rolling in a warm region, the manufacturing information of the corresponding steel strip can be accurately read when the steel tube is disassembled at a later date. It is an object of the present invention to provide a method for printing an inner surface of a steel pipe.

  In order to solve the above problems, the present invention has the following features.

[1] After forming a steel strip into a cylindrical shape, welding both ends in the width direction of the butted steel strip , and further reducing diameter rolling to manufacture a steel pipe, in the manufacturing process of a welded steel pipe, the inner surface side of the steel pipe after forming A method for printing an inner surface of a steel pipe, wherein the production information is printed by a code in which dots are combined in a certain manner when printing the production information on the steel strip.

  [2] The steel pipe inner surface printing method according to the above [1], wherein the ink used for printing contains a heat-resistant material.

  In the present invention, the manufacturing information of the steel strip is printed on the surface of the steel strip by a code combining points in a certain manner, and thereafter when stretched in the tube length direction by high-reduction rolling However, since the positional relationship between the points remains the same, the manufacturing information of the corresponding steel strip can be accurately read when the steel pipe is disassembled at a later date.

  One embodiment of the present invention is described below.

  In this embodiment, after forming the steel strip into a cylindrical shape, as shown in FIG. As shown in FIG. 1 (a), when manufacturing information on the steel strip 17 is printed on the surface of the steel strip that is formed on the inner surface of the steel pipe after the molding, the steel strip 17 before being formed into a cylindrical shape. The manufacturing information is printed by a code in which dots (dots) are combined in a certain manner.

  As a result, even when the printing is stretched in the tube length direction by high-reduction rolling after printing, the positional relationship between the dots remains the same as shown in FIG. 1B, so that the steel tube 13 was disassembled at a later date. In this case, it is possible to accurately read the manufacturing information of the corresponding steel strip.

  The ink used for printing preferably contains a heat resistant material such as ceramics. As a result, even when the ink is heated to a high temperature after printing, the ink is prevented from being oxidized and the printed dots are prevented from becoming unclear.

  In addition, although the case of the ERW steel pipe was described above, the present invention can also be applied to the case of other welded steel pipes (for example, spiral steel pipes) manufactured by forming a steel strip.

It is a figure which shows an example of the steel pipe inner surface printing in one Embodiment of this invention. It is a figure which shows the condition which prints the manufacturing information of a steel strip on the steel strip surface. It is a figure which shows the example which printed the manufacturing information of the steel strip on the steel strip surface. It is a figure which shows the general manufacturing process of an ERW steel pipe.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Coil (coiled steel strip) or skelp 2 Uncoiler 3 Leveler 5 Forming roll 6 Induction heating device 7 Squeeze roll 8 Element steel pipe (element tube)
9 Bead cutting means 10 Cross-cutting machine 13 Steel pipe (ERW steel pipe)
17 Steel strip

Claims (2)

After forming the steel strip into a cylindrical shape, welding both ends in the width direction of the abutted steel strip , and further reducing diameter rolling to manufacture a steel pipe, in the manufacturing process of the welded steel pipe, the steel pipe becomes the inner surface side after forming A method for printing an inner surface of a steel pipe, wherein the production information is printed on a surface of the steel strip by means of a code in which dots are combined in a certain manner when the production information of the steel strip is printed.   2. The steel pipe inner surface printing method according to claim 1, wherein the ink used for printing contains a heat-resistant material.

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