CN204194425U - A kind of pass schedule avoiding large-size round steel face crack - Google Patents

Abstract

The utility model discloses a pass system for avoiding cracks on the _surface of large-scale hot-rolled round steel. The incoming material width B satisfies the following relationship: b _k /B=1.030～1.045. The groove bottom width b _k of the nth pass of rough rolling and the incoming material width B satisfy the following relationship: Bb _k = 0 ~ 3mm. The notch width B _k of the pass shape satisfies the relationship with the maximum value b of the rolled piece width and the widening allowance △ of the pass shape: B _k =b+△. The utility model effectively solves the rolling cracks on the surface of the large-size round steel, and significantly improves the yield of the product.

Description

A pass system for avoiding cracks on the surface of large-scale round steel

technical field

The utility model belongs to the field of metallurgy and relates to a roll pass system, in particular to a pass system for avoiding cracks on the surface of hot-rolled round steel with a diameter of 100 to 180 in large rectangular continuous casting billets.

Background technique

Large-scale round steel with a diameter of φ100～φ180mm is widely used in automobiles, machinery, military industry, petroleum and other industries. At present, such large-size round steel is generally produced by single-stand multi-pass reversible rough rolling plus multi-stand hot continuous rolling with large rectangular billets. In order to facilitate the organization of production and improve the pass commonality, a set of pass system is often used for rough rolling of large-scale round steel with a diameter of φ100 ~ φ180mm. However, due to the large amount of rough rolling deformation and unreasonable rolling temperature, the deformation of the metal particles on the surface of the rolled piece is easy to enter the rheological instability zone, resulting in a large number of crack defects on the surface of the rolled round steel.

Chinese patent ZL 200720129828.2 discloses a device for preventing round steel bars from being scratched. This patent avoids scratches on the surface of round steel by changing sliding friction into rolling friction, thereby improving product quality and production efficiency. This patent solves the crack defects caused by the rolling piece being scratched by auxiliary equipment during the rolling production process, but focuses on the crack defects caused by the rolling process. Chinese patent ZL 200820076362.9 discloses a roll pass structure that avoids wrinkles on the surface of large-scale hot-rolled round steel. The technical solution adopted in this patent is: the width dimension B of the groove bottom of the first pass of the rough rolling mill and the width dimension b of the billet after heating should satisfy the relationship of B-b=3-5mm. This patent notices the influence of the rolling pass on the surface quality of the rolled piece, but only considers the influence of the first pass of rough rolling.

For this reason, designing a set of rough rolling pass system and process suitable for rolling large rectangular billets to produce large-size round steel has very significant significance for improving the production efficiency and yield of products.

Contents of the invention

In order to overcome the defects of the prior art, the purpose of this utility model is to provide a pass system that avoids cracks on the surface of large-scale round steel. The utility model solves the problem of large rectangular continuous casting by rationally selecting the rough rolling pass system of the roughing mill. The problem of surface cracks caused by billet rolling to produce large-size round steel.

The purpose of this utility model is achieved through the following technical solutions:

A pass system for avoiding cracks on the surface of large-scale hot-rolled round steel, characterized in that: the pass system includes a group of n passes; the n=3~5; the first pass to the n pass - The groove bottom width dimension of one pass type: b _k and the incoming material width B entering the pass type for the first time satisfy the following relationship: b _k /B=1.030～1.045; the groove bottom width dimension b of the nth pass type _k and the incoming material width B satisfy the following relationship: Bb _k = 0 ~ 3mm; the groove width B _k of the pass and the maximum value b of the width of the rolled piece out of the pass and the widening allowance △ satisfy the relationship: B _k = b+△; the value of the widening allowance △ is 5-12 mm.

In the present invention, the roll gap S and roll diameter D satisfy the following relationship: S=0.020˜0.025D. The pass height h _k satisfies the following relationship with the notch width B _k , the groove bottom width b _k , the pass side wall slope tanψ and the roll gap S: h _k =(B _k −b _k )/tanψ+S. The value of the side wall slope tanψ is between 10% and 30%. The groove bottom fillet R and the hole height h _k satisfy the following relationship: R=0.1˜0.2×h _k . The notch fillet r and the hole height h _k satisfy the following relationship: r=0.05˜0.15×h _k .

The utility model aims at the problem of surface cracks that occur when large-size round steel with a diameter of φ100-φ180mm is rolled with a large rectangular continuous casting slab. By drawing thermal processing diagrams and simulating metal deformation in the rough rolling process, the surface cracks of large-size round steel are found. The main reason for the defects is that the deformation characteristics of the metal particles on the surface of the round steel are located in the rheologically unstable region of the thermal processing map. By designing a reasonable pass system, the metal particles in the rheologically unstable region can enter the safe zone, thereby effectively avoiding the instability of the surface metal particles during the rolling process and avoiding the generation of surface cracks. Adopting the pass system of the utility model can obviously improve the probability of forming cracks on the surface of large-size round steel, and effectively improve the product yield and production efficiency.

Description of drawings

Fig. 1 is a schematic diagram of a hole shape and a blank of the utility model.

In the figure, 1 is the pass; 2 is the hot blank entering the pass for the first time.

Detailed ways

Example 1

The finished product specification of 320mm×480mm rectangular billet is φ130mmSAE4137 large-size round steel. The rough rolling pass system is designed as follows: the pass system is composed of pass Ⅰ, pass Ⅱ and pass Ⅲ. Among them, the ratio of the groove bottom width b _k of pass type I and pass type II to the width B of the incoming material entering the pass type for the first time is 1.043 and 1.033, respectively. The difference between the groove bottom width b _k of pass type III and the incoming material width B is 1 mm. The notch width B _k of the pass satisfies the relation: B _k =b+△. Where b is the maximum width of the rolled piece out of the pass. The widening allowances △ of the three pass types are 12mm, 5mm and 5mm respectively. Roll gap S=0.021×roll diameter D. Pass height h _k = (notch width B _k - groove bottom width b _k )/ pass side wall slope tanψ + roll gap S, where the values of the three pass side wall slopes tanψ are 26.7%, 18.0 % and 13.3%. Groove bottom fillet R=0.13×hole height h _k . Notch fillet r=0.010×hole height h _k . The rolled pieces are rolled before the odd-numbered rough rolling passes, and the pass reductions are 80mm, 72mm, 50mm, 48mm, 68mm, 53mm and 44mm respectively.

Example 2

The finished product specification of 320mm×480mm rectangular billet is φ150mm25MnCrNiMo large-size round steel. The rough rolling pass system is designed as follows: the pass system is composed of pass type Ⅰ, pass type Ⅱ and pass type Ⅲ. Among them, the ratio of the groove bottom width b _k of pass type I and pass type II to the width B of the incoming material entering the pass type for the first time is 1.043 and 1.033, respectively. The difference between the groove bottom width b _k of pass type III and the incoming material width B is 1 mm. The notch width B _k of the pass satisfies the relation: B _k =b+△. Where b is the maximum width of the rolled piece out of the pass. The widening allowances △ of the three pass types are 12mm, 5mm and 5mm respectively. Roll gap S=0.021×roll diameter D. Pass height h _k = (notch width B _k - groove bottom width b _k )/ pass side wall slope tanψ + roll gap S, where the values of the three pass side wall slopes tanψ are 26.7%, 18.0 % and 13.3%. Groove bottom fillet R=0.13×hole height h _k . Notch fillet r=0.010×hole height h _k . The rolled pieces are rolled before the odd-numbered rough rolling passes, and the pass reductions are 80mm, 72mm, 50mm, 48mm, 68mm, 53mm and 44mm respectively.

Adopting the pass system of the utility model can obviously improve the probability of forming cracks on the surface of large-size round steel, and effectively improve the product yield and production efficiency.

Claims (3)

1. A pass system for avoiding cracks on the surface of large-scale hot-rolled round steel, characterized in that: the pass system includes a group of n passes; the n=3～5; the first pass～ The groove bottom width of the n-1th pass: b _k and the width B of the incoming material entering the pass for the first time satisfy the following relationship: b _k /B=1.030～1.045; the groove bottom width of the nth pass The dimension b _k and the incoming material width B satisfy the following relationship: Bb _k =0~3mm; the notch width B _k of the pass and the maximum value b of the width of the rolled piece out of the pass and the widening allowance △ satisfy the relationship: B _k =b+△; the value of the widening allowance △ is 5-12 mm. 2. The pass system for avoiding cracks on the surface of large-scale hot-rolled round steel according to claim 1, characterized in that: the pass height h _k is related to the notch width B _k , the slot bottom width b _k , and the pass side The wall slope tanψ and the roll gap S satisfy the following relationship: h _k = ( B _k - b _k )/ tanψ + S; the value of the side wall slope tanψ is between 10% and 30%. 3. The pass system for avoiding surface cracks of large-scale hot-rolled round steel according to claim 1, characterized in that: the groove bottom fillet R and the pass height h _k satisfy the following relationship: R=0.1～0.2× h _k ; the notch fillet r and the hole height h _k satisfy the following relationship: r=0.05～0.15×h _k .