CN201376007Y

CN201376007Y - Cold-drawing mold for refining crystalline grains on internal surface of steel pipe

Info

Publication number: CN201376007Y
Application number: CN200920069016U
Authority: CN
Inventors: 王起江; 洪杰; 赵永安
Original assignee: Baoshan Iron and Steel Co Ltd
Current assignee: Baoshan Iron and Steel Co Ltd
Priority date: 2009-03-18
Filing date: 2009-03-18
Publication date: 2010-01-06
Anticipated expiration: 2019-03-18

Abstract

The utility model relates to a cold-drawing steel pipe mold, belonging to the cold-rolling/cold-drawing seamless steel pipe production of the metal plastic molding field. A cold-drawing mold for refining crystalline grains on the internal surface of the steel pipe comprises an external mold and an internal mold, wherein one end of the internal mold is fixedly connected with a pull rod; the internal surface of the external mold consists of a round table shape and a straight hole shape, and the small hole end of the round table shape is connected with the straight hole shape; the external surface of the internal mold consists of a big-diameter cylinder core rod, a small-diameter cylinder core rod and a step; the step is connected with the two cylinder core rods with different diameters, and the step is in arc connection with the two cylinder core rods; the small-diameter cylinder core rod is fixedly connected with the pull rod; and the diameter of the straight hole shape of the external mold is bigger that that of the big-diameter cylinder core rod of the internal mold. For the cold-drawing steel pipe mold, the internal surface of the steel pipe is largely deformed, and the refining effect of the crystalline grains on the internal surface of the steel pipe, so as to improve the oxidation resistance and the vapor corrosion resistance of the steel pipe product.

Description

The cold drawing die of table crystal grain in the refinement steel pipe

Technical field

The utility model relates to a kind of cold drawing steel tube mould, belongs to the cold rolling/solid drawn tube production of field of metal plastic shaping.

Background technology

For the steel pipes that the table antioxygenic property has high requirements in steel pipe such as boiler tube, inner surface has fine grained texture, is very favorable for the antioxygenic property and the anti-steam corrosion performance that improve product.At present in order to show crystal grain in the refinement, thereby improve table antioxygenic property in the steel pipe, can be by the such mechanical processing method of interior peening, but ball blasting method can only be at the lower steel grade of intensity, and complex process, production efficiency is low, cost is high.

Produce for solid drawn tube, existing cold drawing steel tube mould has two kinds.A kind of is general formula steel pipe cold drawing die, and it is made up of taper external mold and cylindricality plug, thus the big refinement appearance crystal grain of steel pipe appearance deformation rate in Cold Drawing Process, interior table deformation rate is very little, and interior table crystal grain does not almost change.Another kind is the Chinese style cold drawing die, it is made up of arc external mold and conic mandrel bar, steel pipe is in process of tube plug drawing mill, interior table can obtain certain machining deformation, but for table crystal grain DeGrain in the refinement steel pipe, its drawbench load is big simultaneously, and internal mold is easy to generate fracture, and the maximum percentage elongation of Chinese style cold drawing die draw steel pipe is less simultaneously.

The utility model content

The purpose of this utility model is to provide the cold drawing die of table crystal grain in a kind of refinement steel pipe, this cold drawing die is by carrying out large deformation to the steel pipe endosexine, the table grain refining effect is obvious in the steel pipe, thereby the antioxygenic property and the anti-steam corrosion performance of tube product have been improved, simultaneously with respect to traditional Chinese style cold drawing die, can increase the maximum percentage elongation of steel pipe, improve die life.

The utility model is achieved in that the cold drawing die of table crystal grain in a kind of refinement steel pipe, comprises external mold and internal mold, the affixed pull bar of internal mold one end, and described external mold inner surface is made up of truncated cone-shaped and straight hole shape, and the truncated cone-shaped small bore end connects straight hole shape; The internal mold outer surface is made up of major diameter cylinder plug, minor diameter cylinder plug and step, and step connects the cylinder plug of two sections different-diameters, and between step and two the cylinder plugs for the circular arc connection, at the affixed pull bar of minor diameter cylinder plug end; External mold straight hole shape diameter is greater than the diameter of internal mold major diameter cylinder plug.

Described step is round table-like, and the step angle is between 30～60 degree, and shoulder height is 0.3～1mm.

The utility model makes steel pipe in cold-drawn by changing the structure of existing cold drawing die, and the thick layer generation large deformation of table 0.5mm-1.5mm obtains certain thickness grain refinement layer in the steel pipe, thereby improves the antioxygenic property of table in the steel pipe.

Cold drawing die of the present utility model is compared with existing general formula mould, increasing angle on the internal mold between 30～60 degree, it highly is the step of 0.3～1mm, large deformation is carried out in the steel pipe endosexine, table obtains the thin crystal layer that thickness is 30-300 μ m in making, thereby improves the antioxygenic property and the anti-steam corrosion performance of product.Compare with existing Chinese style mould, the utility model has increased the drawbench load limitedly, reached the effect of table crystal grain in the refinement, and it is because very big in the thick layer deformation rate of interior table 0.5mm-1.5mm, grain refining effect is more obvious, with respect to the Chinese style cold drawing die, increase the maximum percentage elongation of steel pipe simultaneously, improved die life.

Description of drawings

Fig. 1 is the cold drawing die structural representation of table crystal grain in the utility model refinement steel pipe;

Fig. 2 is the cold drawing die internal mold step place structure enlarged diagram among Fig. 1;

Fig. 3 shows metallograph in the steel pipe after embodiment 1 cold-drawn.

Among the figure: 1 external mold, 2 internal molds, 3 pull bars, 4 steel pipes, 21 major diameter cylinder plugs, 22 minor diameter cylinder plugs, 23 steps.

The specific embodiment

The utility model is described in further detail below in conjunction with the drawings and specific embodiments.

Referring to Fig. 1, Fig. 2, the cold drawing die of table crystal grain comprises external mold 1 and internal mold 2 in a kind of refinement steel pipe, and external mold 1 inner surface is made up of truncated cone-shaped and straight hole shape, and the truncated cone-shaped small bore end connects straight hole shape, and the junction is an arc-shaped transition; Internal mold 2 outer surfaces are made up of major diameter cylinder plug 21, minor diameter cylinder plug 22 and step 23, step 23 connects the

cylinder plug

21,22 of two sections different-diameters, and between step 23 and two the

cylinder plugs

21,22 for circular arc connects, at the affixed pull bar 3 of minor diameter cylinder plug 22 ends; External mold 1 straight hole shape diameter is greater than the diameter of internal mold 2 major diameter cylinder plugs 21.Described step 23 is round table-like, and step 23 angles are between 30～60 degree, and step 23 highly is 0.3～mm.It below is a specific embodiment.

Steel pipe 4 external diameters are 72mm before the cold-drawn, and wall thickness is 7mm, and behind cold drawing die, steel pipe 4 outer diameter D after the cold-drawn are 55mm, and wall thickness t is 6mm.The external mold 1 straight hole shape diameter of described cold drawing die is 55mm, the diameter d 2 and the diameter d 1 of 2 two sections cylinder plugs of internal mold are respectively 42mm and 43mm, internal mold 2 mould step angle α are 50 degree, step 23 highly is 0.5mm, and chamfer radius R1 and R2 are 2.5mm between step 23 and two the cylinder plugs 21,22.Show the metallographic structure photo as shown in Figure 3 in the steel pipe after the cold-drawn, obtain the thin crystal layer that thickness is about 200 μ m.

The utility model is by carrying out large deformation to the steel pipe endosexine, and the table grain refining effect is obvious in the steel pipe, thereby has improved the antioxygenic property and the anti-steam corrosion performance of tube product, has increased the maximum percentage elongation of steel pipe simultaneously, has improved die life.

Claims

1, the cold drawing die of table crystal grain in a kind of refinement steel pipe comprises external mold and internal mold, and the affixed pull bar of internal mold one end is characterized in that: the external mold inner surface is made up of truncated cone-shaped and straight hole shape, and the truncated cone-shaped small bore end connects straight hole shape; The internal mold outer surface is made up of major diameter cylinder plug, minor diameter cylinder plug and step, and step connects the cylinder plug of two sections different-diameters, and between step and two the cylinder plugs for the circular arc connection, at the affixed pull bar of minor diameter cylinder plug end; External mold straight hole shape diameter is greater than the diameter of internal mold major diameter cylinder plug.

2, the cold drawing die of table crystal grain in the refinement steel pipe according to claim 1, it is characterized in that: described step is round table-like, and the step angle is between 30～60 degree, and shoulder height is 0.3～1mm.