JP2008114240A - Glass pad forming tool for hot extrusion - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a glass pad forming tool for manufacturing a steel pipe by hot extrusion. <P>SOLUTION: The glass pad forming tool for manufacturing the steel pipe by hot extrusion has its inside surface formed in such a manner that the thickness of the glass pad decreases from its middle portion to the inside surface. Further, the angle of the inside surface of the glass pad forming tool is set to be 20 to 60°. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a glass pad forming tool for hot extrusion for producing a steel pipe by hot extrusion.

  Conventionally, when manufacturing a steel pipe by hot extrusion, a glass disk is used as a lubrication disk for hot extruded steel pipe on the billet side of the die, whose inner diameter is slightly larger than the inner diameter of the die and whose maximum outer diameter is substantially equal to the inner diameter of the container. It is installed. This glass disk is formed by solidifying and drying granular glass into a disk shape with a binder such as water glass. The glass disk at this time acts as a lubricant between the die and the billet.

  In the case of manufacturing a steel pipe by hot extrusion, the glass disk has an unmelted glass disk that scratches the tip of the billet to form a “streak”. FIG. 5 is a schematic view showing a muscle lees. FIG. 5A is a side view, and FIG. 5B is a top view. As shown in this figure, a stirrup 19 is formed on the steel pipe 18. Also, at the beginning of extrusion, the glass disk softens in a large amount, and since this softened glass does not exert a uniform lubricating action in the circumferential direction, a part of the billet in the circumferential direction is pushed out in advance, resulting in deformation. In the tube circumferential direction of the outer surface of the extruded tube, there is a problem that irregularities occur at the tip.

As a method for solving the above problem, for example, as disclosed in JP-A-4-270008, it is made of a glass fiber paper product, a woven fabric or a stack, and its carbon content is 1% or less. A front lubrication disk for extruded pipes and a method for producing the same have been proposed.
JP-A-4-270008

  However, the above-described front lubrication disk for hot-extruded pipes in Patent Document 1 has been solved so that the problems related to “streak” and the like, but the glass pad of the conventional method is molded to have a constant thickness, The tip of the steel pipe immediately after extrusion was stretched while contacting the inner surface of the glass pad, and received resistance, resulting in a non-uniform tip shape. In particular, when manufacturing a thin extruded steel pipe, the tip of the steel pipe extends unevenly due to the difference in resistance of the glass pad, resulting in a defective shape of the tip of the steel pipe as shown in FIG. The reality is that the problem is not solved because of quality problems.

  In order to solve the above-mentioned problems, the inventors have made extensive developments. As a result, the present invention reduces the thickness of the glass from the central portion to the inner surface portion, thereby reducing the resistance of the inner surface portion. Is obtained, and a good tip shape of the extruded steel pipe is obtained. It is an object of the present invention to provide a hot-extrusion glass pad molding tool capable of preventing the occurrence of a linear outer surface flaw that occurs from the front end to the rear end when it has a good tip shape.

The gist of the invention is that
(1) An extrusion molding tool for producing a steel pipe by hot extrusion, characterized in that the inner surface of the glass pad molding tool has a shape in which the thickness of the glass pad is reduced from the center to the inner surface. Glass pad molding tool for extrusion.
(2) A glass pad forming tool for hot extrusion, wherein the angle of the inner surface of the glass pad forming tool according to (1) is set to 20 to 60 °.
(3) Glass for hot extrusion, characterized in that the glass pad outer diameter is 100 to 300 mm, the inner diameter is 20 to 200 mm, and the thickness is 10 to 40 mm of the glass pad molding tool according to (1) or (2). It is in a pad molding tool.

  As described above, according to the present invention, an excellent tip shape of an extruded steel pipe is obtained. That is, it is possible to prevent the occurrence of a linear outer surface flaw that occurs from the front end to the rear end, and in particular, it is possible to improve the outer surface flaw defect rate of a thin steel pipe having a thickness of 4 mm or less and to improve the quality. It is effective.

Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic view showing a steel pipe extrusion method and a die by a hot extrusion method. As shown in FIG. 1, a die holder 3 is attached to one end of a holder having a container liner 2 in a liner holder 1, and a packing ring 4 and a die 5 are disposed in the die holder 3. Is provided with a glass pad 6 and charged with a billet 7 which is heated from the other end, and is extruded from a bolster liner 11 by means of a hollow stem 10 equipped with a mandrel adapter 9 via a blessing disk 8. The billet 7 has a predetermined shape through the die 5 and the inner diameter is a parallel shape because it determines the outer diameter of the extruded material. Reference numeral 12 denotes a mandrel, and reference numeral 18 denotes a steel pipe.

  FIG. 2 is a cross-sectional view and a side view of the glass pad portion according to the present invention. 2A is a cross-sectional view, and FIG. 2B is a side view. As shown in this figure, the glass pad portion is composed of an outer surface portion 13, a central portion 14 and an inner surface portion 15, and the glass pad hitting the inner surface portion is a straight line 16 at the same angle from the central portion 14. The glass thickness is reduced over the inner surface portion 15. In other words, the inner surface portion 15 of the glass pad is gradually decreased like the decreasing portion 17. Thus, the present invention reduces the unnecessary glass that produces the resistance of the inner surface portion by reducing the thickness of the glass pad from the central portion to the inner surface portion, and obtains a good tip shape of the extruded steel pipe. In the case of a good tip shape, it is possible to prevent the occurrence of a linear outer surface flaw that occurs from the tip to the rear end.

  FIG. 3 is an enlarged view of the glass pad forming tool. FIG. 3A is a glass pad molding tool according to the present invention, and FIG. 3B is a conventional glass pad molding tool. As shown in this figure, the angle of the inner surface of the molding tool in the conventional case is 5 to 15 ° (8 ° in the drawing) and is 20 to 60 ° (30 ° in the drawing) in the present invention. If it is less than 20 °, the effect of the present invention is not sufficient, and if it exceeds 60 °, the effect is saturated, so the range is set to 20 to 60 °. The angle is preferably 25 to 40 °.

  By giving such an angle, the thickness of the inner surface portion of the glass pad is gradually reduced as shown by the reduction portion 17 in FIG. In this way, by designing and producing a shape in which the inner surface of the glass pad molding tool is projected and used, the molded glass pad gradually becomes thinner from the center to the inner surface. When used in a press machine, the glass resistance at the tip of the steel pipe is reduced, the resistance difference in the circumferential direction is reduced, and a steel pipe capable of obtaining uniform elongation in the circumferential direction can be manufactured.

  The glass pad outer diameter of the glass pad molding tool is 100 to 300 mm. The effect of achieving the present invention is not sufficiently obtained with a glass pad molding tool of less than 100 mm, and the range is set to 100 to 300 mm because it is not suitable for the manufacture of steel pipes that exceed 300 mm. Preferably it is set to 150-250. The inner diameter is 20 to 200 mm. If it is less than 20 mm, the effect is not sufficient, and if it exceeds 200 mm, it is not suitable from the outside diameter. Therefore, the range is 20 to 200 mm, preferably 50 to 150 mm. Furthermore, the thickness was 10 to 40 mm. If it is less than 10 mm, the effect is not sufficient, and exceeding 40 mm is not suitable from the outer diameter and the inner diameter, so the range was set to 10 to 40 mm. Preferably it is 15-30.

  FIG. 4 is a diagram showing a steel pipe tip shape. Fig.4 (a) is a figure which shows the front-end | tip part of the steel pipe at the time of implementing using the glass pad shaping | molding tool for hot extrusion which concerns on this invention, and a front-end | tip shape defective part becomes in the range of 0-100 mm in general. FIG.4 (b) is a figure which shows the front-end | tip part of the steel pipe 18 at the time of implementing using the conventional glass pad shaping | molding tool for hot extrusion, and it is harmful when a front-end | tip shape defect part exceeds about 100 mm. As can be seen from this figure, in the case of the present invention, the tip portion and the central portion of the steel pipe are uniformly extruded. On the other hand, in the conventional case, it can be seen that a defective portion is generated in the tip shape.

Hereinafter, the present invention will be specifically described with reference to examples.
First, in producing a glass pad molding tool, glass powder is prepared, and a glass pad is molded by mixing a glass binder, for example, a binder such as water glass. Then, after sintering and drying, it is conveyed to extrusion, and a glass pad is inserted into a die holder. On the other hand, in the extrusion process, a billet made of SUS304 was inserted into the container to perform hot extrusion pipe making. The heating temperature of the billet is 1220 ° C, the dimensions of the extruded tube are an outer diameter of 45 mm, a thickness of 3 mm, and an extrusion ratio of 25.0. In parallel with this, each glass pad having an outer diameter, an inner diameter, and a thickness shown in Table 1 was used to produce a pipe. After that, the product is made in the order of correction, refining, and inspection. As the glass pad shape in that case, the inner angle of the molding tool, the outer diameter, the inner diameter, and the thickness of the glass pad and the linear outer surface wrinkle were examined. At that time, evaluation was made with no external flaws: ○, wrinkles that were not a problem as a product: Δ, and defective products: ×.

  As shown in Table 1, no. 1-8 are examples of the present invention. 9 to 17 are comparative examples. Comparative Example No. No. 9 to 11 have a linear outer surface flaw which occurs as a harmful flaw extending from the front end to the rear end of the steel pipe because the inner surface angle of the glass pad forming tool does not satisfy the conditions of the present invention. As a defective product. Comparative Example No. Any of Nos. 12 to 14 has a linear outer surface that occurs as a harmful flaw extending from the front end to the rear end of the steel pipe because any of the outer diameter, inner diameter, and thickness of the glass pad does not satisfy the conditions of the present invention. As a result, defects occurred and the product became defective.

  Further, Comparative Example No. Nos. 15 to 17 indicate that the inner surface angle of the glass pad molding tool does not satisfy the conditions of the present invention, and any of the outer diameter, inner diameter and thickness of the glass pad does not satisfy the conditions of the present invention. The product was a defective product due to the linear outer surface flaws generated as harmful flaws extending toward the rear end. On the other hand, the present invention No. 1 to 8 all satisfy the conditions of the present invention, and as a result, it was found that good steel pipes without defects were obtained.

以上のように、熱管押出で鋼管を製造する場合において、潤滑用ガラスパットの従来形状と比較して、所定の形状に成型し、ガラスパット厚さを調整することにより、良好な鋼管の先端形状を得ることができる。その結果、押出鋼管は先端形状を改善することで鋼管先端から後端部分まで延びる有害な外面疵を減少させることができる極めて優れた効果を奏するものである。

As described above, when manufacturing a steel pipe by hot-tube extrusion, the tip shape of a good steel pipe can be obtained by molding it into a predetermined shape and adjusting the thickness of the glass pad compared to the conventional shape of a lubricating glass pad. Can be obtained. As a result, the extruded steel pipe has an extremely excellent effect that the harmful outer surface flaw extending from the steel pipe front end to the rear end portion can be reduced by improving the tip shape.

It is the schematic which shows the extrusion method and die | dye of the steel pipe by a hot extrusion method. It is sectional drawing and the side view of the glass pad part which concern on this invention. It is an enlarged view of a glass pad molding tool. It is a figure which shows the steel pipe tip shape. It is the schematic which shows a muscle leopard.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liner holder 2 Container liner 3 Die holder 4 Packing ring 5 Dies 6 Glass pad 7 Billet 8 Blessing disk 9 Mandrel adapter 10 Hollow stem 11 Bolster liner 12 Mandrel 13 Outer part 14 Central part 15 Inner part 16 Linear 17 Decreasing part 18 Steel pipe 19 Streak


Patent Applicant Sanyo Special Steel Co., Ltd.
Attorney Atsushi Shiina

Claims (3)

A glass for hot extrusion, which is an extrusion molding tool for manufacturing a steel pipe by hot extrusion, and has a shape in which the inner surface of the glass pad molding tool is reduced from the center to the inner surface. Putting tool. The glass pad molding tool for hot extrusion, wherein the angle of the inner surface of the glass pad molding tool according to claim 1 is 20 to 60 °. A glass pad molding tool for hot extrusion, wherein the glass pad molding tool according to claim 1 has an outer diameter of 100 to 300 mm, an inner diameter of 20 to 200 mm, and a thickness of 10 to 40 mm.

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