Adjustment method of rolling mill stand before high-precision rolling of large bars

Abstract

This invention relates to a method for adjusting a rolling mill stand before high-precision rolling of large bars. The rounding stand is located after the finishing mill stand. The adjustment method involves: determining the aluminum bar size based on the pass dimensions of the previous rolling mill stand; each rolling mill stand after the previous one, except for the last one, continuously rolling the aluminum bar twice, with the last one rolling the aluminum bar once; after the first rolling of the aluminum bar on each rolling mill stand: based on the initial pass height of the rolling mill stand and the dimensions of the aluminum bar after its first pass through the rolling mill stand, obtaining the bounce value of the rolling mill stand; and adjusting the pass height of the rolling mill stand based on the bounce value. This invention allows for adjustment of the rounding mechanism before rolling large bars to ensure that the dimensions of the first rolled bar are controllable and meet standards, avoiding the first rolled bar being substandard.

Description

Technical Field

[0001] This invention relates to the field of large bar rolling, and specifically to a method for adjusting the rolling mill stand before high-precision rolling of large bars. Background Technology

[0002] When rolling large bars (Φ130-Φ200), due to unstable dimensional control and large out-of-roundness, dimensional deviations are often found. Therefore, a gauge rolling mill is added after the finished product stand. Currently, the height of the gauge rolling mill is adjusted according to the size of the first rolled bar after passing through the gauge rolling mill. This results in the first rolled bar being unqualified, long debugging time, and significant waste. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a method for adjusting the rolling mill stand before high-precision rolling of large bars. It can adjust the rolling mill stand before rolling large bars to ensure that the size of the first rolled bar is controllable and meets the standard, and avoid the first rolled bar being unqualified.

[0004] To solve the above-mentioned technical problems, the technical solution of the present invention is: a method for adjusting the rolling mill stand before high-precision rolling of large bars, comprising:

[0005] The aluminum bar is designed based on the die size of the previous rolling mill stand;

[0006] Each rolling mill stand following the preceding rolling mill stand, according to the rolling sequence, except for the last rolling mill stand, continuously rolls the aluminum bar twice per rolling mill stand, and rolls the aluminum bar once per rolling mill stand; wherein, after the first rolling of the aluminum bar in each rolling mill stand:

[0007] Based on the initial pass height of the rolling mill stand and the dimensions of the aluminum bar after its first pass through the rolling mill stand, the bounce value of the rolling mill stand is obtained, and the pass height of the rolling mill stand is adjusted based on the bounce value of the rolling mill stand.

[0008] Furthermore, the rolling mill following the previous rolling mill stand has three stands: a pre-finishing stand K2, a finished product stand K1, and a rounding stand K0. The die shape of the pre-finishing stand K2 is elliptical, while the die shapes of the finished product stand K1 and the rounding stand K0 are circular. The adjustment method specifically includes:

[0009] The rolling mill following the previous rolling mill stand has three stands: the pre-finishing mill stand K2, the finished product mill stand K1, and the rounding mill stand K0. The die shape of the pre-finishing mill stand K2 is elliptical, while the die shapes of the finished product mill stand K1 and the rounding mill stand K0 are circular. The adjustment method specifically includes:

[0010] After the specified aluminum bar enters the finishing mill stand K2 for rolling, an elliptical aluminum bar with a height * width of H2 * B2 is obtained. H2 is compared with the die height of the finishing mill stand K2 to obtain the bounce value △h2 of the finishing mill stand K2. The die height △h2 of the finishing mill stand K2 is adjusted and reduced. The elliptical aluminum bar with a height * width of H2 * B2 is rolled again through the finishing mill stand K2 to obtain a material shape with a height * width of H3 * B3.

[0011] A material with a height * width of H3 * B3 is rolled in the finishing mill stand K1 to obtain material shape Dn. The D1 value in the height direction is measured and compared with the pass height of the finishing mill stand K1 to obtain the bounce value △h1 of the finishing mill stand K1. The pass height △h1 of the finishing mill stand K1 is adjusted to reduce it, and material shape Dn is rolled again in the finishing mill stand K1 to obtain material shape D. n+1 ;

[0012] Material shape D n+1 After entering the rolling mill stand K0, the material shape D0 is obtained. The value of D0′ in its height is measured. The value of D0′ is compared with the die height of the rolling mill stand K0 to obtain the bounce value △h0 of the rolling mill stand K0. The die height △h0 of the rolling mill stand K0 is adjusted to be reduced.

[0013] Furthermore, the base circle of the rounding mill stand K0 has the same size as the base circle of the finished product stand K1, which is the required specification size of the rolled material multiplied by the coefficient of thermal expansion.

[0014] Furthermore, the slot of the circular gauge frame K0 is 3mm larger than the slot of the finished product frame K1.

[0015] Furthermore, the relationship between the initial hole height H of the finished product frame K1 and the finished product diameter D is H = (D - 0.3 mm) * coefficient of thermal expansion;

[0016] The relationship between the initial hole width B of the finished product frame K1 and the finished product diameter D is B = (D + 1mm) * coefficient of thermal expansion.

[0017] Furthermore, to prevent bending of the rolled piece head and the formation of ears, wires, etc., the roll gap of the rounding mill stand K0 is larger than the roll gap of the finished product stand K1.

[0018] By adopting the above technical solution, before high-precision rolling of large bars, the present invention uses aluminum bars to measure the bounce value of each rolling mill stand during the rolling process. Then, the pass height of each rolling mill stand can be adjusted according to the bounce value. By adjusting the pass of the rolling mill stand in this way, the size of the first rolled material can be controlled and meets the production requirements, thus avoiding the first rolled material being unqualified. Attached Figure Description

[0019] Figure 1 The hole pattern of the finished front frame K2 of the present invention;

[0020] Figure 2The hole pattern of the finished frame K1 of the present invention;

[0021] Figure 3 The hole type of the circular frame K0 of the present invention. Detailed Implementation

[0022] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments.

[0023] A method for adjusting the rolling mill stand before high-precision rolling of large bars includes:

[0024] The aluminum bar is designed based on the die size of the previous rolling mill stand;

[0025] Each rolling mill stand following the preceding rolling mill stand, according to the rolling sequence, except for the last rolling mill stand, continuously rolls the aluminum bar twice per rolling mill stand, and rolls the aluminum bar once per rolling mill stand; wherein, after the first rolling of the aluminum bar in each rolling mill stand:

[0026] Based on the initial pass height of the rolling mill stand and the dimensions of the aluminum bar after its first pass through the rolling mill stand, the bounce value of the rolling mill stand is obtained, and the pass height of the rolling mill stand is adjusted based on the bounce value of the rolling mill stand.

[0027] In one embodiment, such as Figure 1 , 2 As shown in Figure 3, the rolling mill following the previous rolling mill has three stands: the pre-finishing mill stand K2, the finished product mill stand K1, and the circular mill stand K0. The die shape of the pre-finishing mill stand K2 is elliptical, while the die shapes of the finished product mill stand K1 and the circular mill stand K0 are circular. K1 is a vertical rolling mill; K2 and K0 are horizontal rolling mills. The adjustment method specifically includes:

[0028] After the specified aluminum bar enters the finishing mill stand K2 for rolling, an elliptical aluminum bar with a height * width of H2 * B2 is obtained. H2 is compared with the die height of the finishing mill stand K2 to obtain the bounce value △h2 of the finishing mill stand K2. The die height △h2 of the finishing mill stand K2 is adjusted and reduced. The elliptical aluminum bar with a height * width of H2 * B2 is rolled again through the finishing mill stand K2 to obtain a material shape with a height * width of H3 * B3.

[0029] A material with a height * width of H3 * B3 is rolled in the finishing mill stand K1 to obtain material shape Dn. The D1 value in the height direction is measured and compared with the pass height of the finishing mill stand K1 to obtain the bounce value △h1 of the finishing mill stand K1. The pass height △h1 of the finishing mill stand K1 is adjusted to reduce it, and material shape Dn is rolled again in the finishing mill stand K1 to obtain material shape D. n+1 ;

[0030] Material shape D n+1After entering the rolling mill stand K0, the material shape D0 is obtained. The value of D0′ in its height is measured. The value of D0′ is compared with the die height of the rolling mill stand K0 to obtain the bounce value △h0 of the rolling mill stand K0. The die height △h0 of the rolling mill stand K0 is adjusted to be reduced.

[0031] In one embodiment, the base circle of the rounding stand K0 has the same size as the base circle of the finished product stand K1, which is the required size of the rolled material multiplied by the coefficient of thermal expansion.

[0032] The slot of the rounding frame K0 is 3mm larger than the slot of the finished product frame K1. The rounding hole presses down the material shape, which will cause it to expand. This setting can prevent the finished product from being overfilled.

[0033] The relationship between the initial hole width B and the finished product diameter D of the pre-adjusted finished product frame K1 is B = (D + 1mm) * coefficient of thermal expansion. 1mm is set as the millimeter-level unit reduction for the material shape of the circular hole; a large reduction makes it difficult to control the material shape.

[0034] The relationship between the initial hole height H of the finished product frame K1 before adjustment and the finished product diameter D is H = (D - 0.3 mm) * thermal expansion coefficient; the width expansion coefficient of steel in the round hole is 0.3, and the free width expansion is 0.3 mm for every 1 mm reduction.

[0035] The coefficient of thermal expansion is generally selected when the final rolling temperature is around 990 degrees Celsius, and is usually 1.008.

[0036] The roll gap of the rounding mill stand K0 is larger than that of the finishing mill stand K1. This design prevents the head of the rolled piece from bending and causes issues such as earing and wire drawing.

[0037] The technical solutions in the above embodiments will be described in detail below with reference to specific examples.

[0038] In this embodiment, a round gauge stand is installed on the empty pass stand after the finished product stand, taking 130mm round rolling as an example:

[0039] According to the process material dimensions, the height of each pass's die is measured using internal calipers, and the initial die height is adjusted accordingly: K2 height 125mm, K1 height 130.7mm, and K0 height 131mm. Then, a 154mm*155mm aluminum bar is rolled through the K2 stand before the finished product, resulting in a material shape with a height*width of 126mm*147.7mm. The die height of K2 is then reduced by 1mm, and the material shape with a height*width of 126mm*147.7mm is rolled again through K2, resulting in a material shape with a height*width of 125mm*148mm. Then... A 125mm x 148mm blank is rolled on the K1 finishing stand to obtain a 131.5mm x 131.8mm blank. The height of the K1 pass is then reduced by 0.8mm. This 131.5mm x 131.8mm blank is then rolled again on the K1 stand to obtain a 130.7mm x 132mm blank. Finally, this 130.7mm x 132mm blank is rolled on the K0 stand to obtain a 131.5mm x 130.9mm blank. The height of the K0 pass is then reduced by 0.5mm. The advantage of this process is that the dimensions of the first rolled blank are controllable and meet standard tolerance requirements, avoiding a defective first blank.

[0040] The first rolling of the aluminum bar by K2 and K1 is to obtain the bounce value, and the second rolling of the aluminum bar is to obtain the process material shape so that the aluminum bar can continue to enter the next rolling stand for calibration to obtain the bounce value.

[0041] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for adjusting a rolling stand before high-precision rolling of a large bar, comprising: based on the pass size of a previous rolling stand, making an aluminum bar; each rolling stand after the previous rolling stand, except the last rolling stand, continuously rolls the aluminum bar twice, and the last rolling stand rolls the aluminum bar once; wherein after the first rolling of the aluminum bar in each rolling stand: based on the initial pass height of the rolling stand and the size of the aluminum bar after the first rolling, obtaining the springback value of the rolling stand, and adjusting the pass height of the rolling stand based on the springback value of the rolling stand; the rolling stands after the previous rolling stand have three, in order, a pre-finished product stand K2, a finished product stand K1, and a roundness stand K0, the pass of the pre-finished product stand K2 is an ellipse, and the passes of the finished product stand K1 and the roundness stand K0 are circles, and the adjusting method specifically comprises:

2. The method for adjusting a rolling stand before high-precision rolling of a large bar according to claim 1, wherein:

3. The method for adjusting a rolling stand before high-precision rolling of a large bar according to claim 1, wherein: The slot of the roundness stand K0 is 3 mm larger than the slot of the finished product stand K1.

4. The method for adjusting a rolling stand before high-precision rolling of a large bar according to claim 1, wherein:

5. The method for adjusting a rolling stand before high-precision rolling of a large bar according to claim 1, wherein: The aluminum bar is rolled by the prepared pre-finished rack K2, and high The width is H2 The oval aluminum bar B2 is rolled by the pre-finished rack K2 again, and high The width is H2 The oval aluminum bar B2 is rolled by the pre-finished rack K2 again, and high The width is H3 The material shape B3 High The width of B3 is H3 The profile Dn is obtained after the profile B3 is rolled into the finished rack K1. The D1 value in the height direction is measured. The D1 value is compared with the finished rack K1 pass height, and the finished rack K1 spring value Ah1 is obtained. The finished rack K1 pass height Ah1 is adjusted and reduced. The profile Dn is rolled into the finished rack K1 again, and the profile D n+1 is obtained. Material shape D n+1 After entering the roundness adjusting stand K0 rolling, material shape D0 is obtained, the value of D0' in the height is measured, the value of D0' is compared with the roundness adjusting stand K0 pass height, the roundness adjusting stand K0 springback value Δh0 is obtained, and the roundness adjusting stand K0 pass height Δh0 is adjusted and reduced. The roll gap of the roundness stand K0 is larger than the roll gap of the finished product stand K1. The base circle of the sizing stand K0 has the same size as the base circle of the finished stand K1 and is the desired gauge size for the rolled material Coefficient of thermal expansion. ​ ​ ​ The relationship between the initial pass height H of the finished rack K1 and the finished diameter D is H=(D-0.3mm) Coefficient of thermal expansion The initial pass width B of the finished rack K1 is related to the finished diameter D as B = (D + 1 mm) Thermal expansion coefficient. ​ ​

Images