CN1857809A - Dynamic thickening rolling process of controlling break of cold rolled thin strip steel - Google Patents

Abstract

The dynamic thickening rolling process of controlling break of cold rolled thin strip steel has weld seam tracking system used in measuring the weld seam position accurately, and features that in the range of 50 m around the weld seam, the strip steel thickness is increased to 1.0-1.5 times the original target thickness. Two wedge rolling processes are used to increase the rolled thickness dynamically, so as to lower the break rate of the thin rolled material. The present invention has the advantages of reduced strip steel breaking rate, high production efficiency, etc. and is suitable for multi-frame continuous cold rolling machine with 4, 5 or 6 frames.

Description

A kind of dynamic thickening rolling process of controlling break of cold rolled thin strip steel

Technical field

The invention belongs to metal material pressure processing field, relate in particular to the dynamic thickening rolling process of control cold continuous rolling strip steel broken belt.

Background technology

In the prior art, rolling thin specification cold-strip steel ubiquity broken belt rate height, production efficiency is low, lumber recovery is low technical barrier, particularly thickness are more outstanding less than the product problem of 0.3mm.With certain factory's 4 frames, four roller cold continuous rolling is example, and thickness up to 28.7%, causes lumber recovery low less than the band steel broken belt rate of 0.5mm, and the downtime of causing because of broken belt is longer, thereby causes production efficiency low.Therefore, the product of thickness below 0.3mm can not be produced basically.

For this reason, once 5 frame cold continuous rollings were carried out transformation.After transforming, though can produce the product of thickness less than 0.5mm, broken belt rate still is about 11%.Reach more than 40 hours the every month downtime of causing because of broken belt, is equivalent to every month nearly 8000 tons of production capacities of loss.Lumber recovery is low and the production capacity loss is mostly direct and caused enormous economic loss to enterprise indirectly, and its root is exactly because due to the rolling broken belt rate height.Random statistical has been analyzed 200 volume thickness less than the normal situation of broken belt when rolling of 0.5mm band steel, and is as shown in table 1.

Table 15 frame cold continuous rolling broken belts statistics

The broken belt position	In 50 meters of the weld seam front and back	Beyond 50 meters of the weld seam front and back	Add up to
				Broken belt volume number	18	4	22
Broken belt rate	9.0％	2.0％	11.0％

As can be seen from Table 1, the broken belt majority occurs in the 50 meters scopes in weld seam front and back.Main cause is:

1) the plasticity ratio mother metal of commissure band steel is poor, is broken easily;

2) weld seam front and back belt steel plate shape, thickness fluctuation are big, cause tension fluctuation easily, produce broken belt;

3) the raw material defective generally all concentrates near the weld seam, and the part is easy to generate breach, causes broken belt;

4) the band steel is in when rising braking section, tension fluctuation than stable state a lot of greatly, excessive tension force pulling off strips steel.

Summary of the invention

In order to overcome the deficiencies in the prior art, the present invention is directed to the technical characterstic of multimachine frame cold continuous rolling, developed a kind of dynamic thickening rolling process of controlling break of cold rolled thin strip steel.It is to utilize the existing seam tracking system of cold continuous rolling, accurately measure the position while welding of band steel, it is characterized in that taking place easily the phenomenon of broken belt at the weld seam front and back band steel, in the 50 meters scopes in weld seam front and back, the 1.0-1.5 that belt steel thickness is increased to former target thickness doubly, and by two wedge rolling processes realize economic, practical, produce the purpose of high-quality thin specification cold-rolled wide strip steel efficiently.Produce the technical barrier of thickness thereby solved less than the 0.5mm cold-rolled thin steel strip.

The present invention will control the key that the broken belt conduct before and after the cold continuous rolling band steel weld seam is dealt with problems.Its core is in a certain scope, belt steel thickness to be rolled into a certain numerical value that is higher than setting value before and after weld seam, becomes 0.45mm as the belt steel rolling with 0.3mm, thereby reduces the coefficient of tension N value of this segment length band steel, reduces the broken belt risk, reduces broken belt.Coefficient of tension N value is high more, and the trend of band steel broken belt is strong more; Broken belt will take place greater than 1 the time in the coefficient of tension N value that causes moment when a certain fluctuation.

Technical scheme of the present invention is to set computing formula according to the strip tension of cold continuous rolling,

That is: T=BhNRm (1)

Derive from formula (1): N=T/BhRm (2)

In the formula: the width of B-band steel;

The thickness of h-band steel;

The N-coefficient of tension is generally at 0.2-0.3;

The tensile strength of Rm-band steel.

Can intuitively find out from formula (2), act on that the tension force T of band on the steel reduces, strip width B increases, thickness h increases, intensity Rm improves, all can reduce the broken belt risk of band steel.

Before and after weld seam, in a certain scope, utilize the existing seam tracking system of cold continuous rolling, accurately measure the position of weld seam.When the distance of weld pitch the 1st frame be L (during L＜50m), by formula (3) begin to start first wedge rolling process--the process that thickness increases;

That is:

$h_1=h_0+K\·{\∫}_0^{t}v\·\mathrm{dt}---\left(3\right)$

In the formula: h ₁-target thickness, h ₁＜0.85mm;

h ₀-setting thickness, h ₀＜0.85mm;

The K-slope, K=(h ₁-h ₀)/L, K＜1;

The mill speed of v-milling train, v＜5m/s;

After weld seam entered first frame, by formula (4) started the process that second wedge rolling process-thickness reduces, and the length of control band steel is similarly L;

That is: $h_2=h_1-K{\·\∫}_0^{t}v\·\mathrm{dt}---\left(4\right)$

In the formula: h ₁-target thickness, h ₁＜0.85mm;

h ₂-target thickness, h usually ₂=h ₀, h ₂＜0.85mm;

The K-slope, K=(h ₁-h ₀)/L, K＜1;

The mill speed of v-milling train, v＜5m/s;

Above-mentioned parameter is calculated automatically and is delivered in the control system, utilize existing seam tracking system, when weld seam arrival 1# frame front distance is L rice, start first wedge rolling process; When weld seam arrived the 1# frame, the first wedge rolling process was closed, and second wedge rolling process opened; After weld seam is L rice by 1# frame distance, stop second wedge rolling process, system switches to normal THICKNESS CONTROL program.

The technology of the present invention is applicable to multimachine frame fully continuous type cold continuous rollings such as 4 frames, 5 frames and 6 frames, and near band steel thickness weld seam presses straight line or high order curve changes.Its application has overcome the deficiencies in the prior art, has that broken belt rate is low, lumber recovery is high, unit operation efficient advantages of higher.Using rolling thickness with the technology of the present invention in 5 frame tandem mills is example less than the band steel of 0.5mm, and the statistics of picked at random 200 volume creation datas is listed table 2 in.

Table 2 is used the rolling situation statistics of the present invention

The broken belt position	In 50 meters of the weld seam front and back	Beyond 50 meters of the weld seam front and back	Add up to
				Broken belt volume number	6	2	8
Broken belt rate	3.0％	1.0％	4.0％

Contrast as can be seen from table 1 and table 2, the broken belt quantity of thin specification band steel reduces greatly, and broken belt rate has been reduced to 4%, the effect highly significant from 11%.Because broken belt rate reduces greatly, thickness improves 0.9% on year-on-year basis less than the lumber recovery of 0.5mm band steel, shortened in 10 hours the downtime of causing because of the 50 meters broken belts in weld seam front and back in every month, increase by 6000 tons/month of production capacity on year-on-year basis, thereby also reduce about 60 yuan/ton of the interior ton steel costs of this thickness specification limit, have good economic benefit.

The specific embodiment

On probation according to technology provided by the invention at 5 frame cold continuous rollings, the thin slab product of production 0.3mm, control procedure and technological parameter are as follows:

1) strip width B=1030mm, tensile strength Rm=600Mpa, final pass tension force T=3078Kg;

2) near the mill speed v=3.0m/s the weld seam;

3) set belt steel thickness h ₀, h ₂(h ₂=h ₀) and target thickness h ₁, h ₂=h ₀=0.3mm, h ₁=0.45mm;

4) set the distance L of control point, get L=10m to weld seam;

5) application of formula (3), (4) calculate slope K=1.5*10 ^-5

6) above-mentioned parameter calculates automatically and is delivered in the control system;

7) utilize existing seam tracking system, when weld seam arrival 1# frame front distance is L=10m, start first wedge rolling process;

When 8) weld seam arrived the 1# frame, the first wedge rolling process was closed, and second wedge rolling process opened;

9) after weld seam is L=10 rice by 1# frame distance, stop second wedge rolling process;

10) switch to normal THICKNESS CONTROL program.

Claims (3)

1. a dynamic thickening rolling process of controlling break of cold rolled thin strip steel utilizes the existing seam tracking system of cold continuous rolling, accurately measures the position while welding of band steel; Its major technique is characterised in that: before and after band steel weld seam in 50 meters scopes, the 1.0-1.5 that belt steel thickness is increased to former target thickness doubly and realizes that by two wedge rolling processes local dynamic thickening is rolling.

2. a kind of dynamic thickening rolling process of controlling break of cold rolled thin strip steel according to claim 1 is characterized in that: the strip tension according to cold continuous rolling is set computing formula, two wedge rolling control formula below having derived,

That is: $h_1=h_0+K\·{\∫}_0^{t}v\·\mathrm{dt}$

$h_2=h_1-K\·{\∫}_0^{t}v\·\mathrm{dt}$

In the formula: the thickness of h-band steel;

h ₀-setting thickness;

h ₁-target thickness;

h ₂-target thickness, h usually ₂=h ₀

The K-slope, K=(h ₁-h ₀)/L, L is the distance of control starting point to the band steel;

The mill speed of v-milling train.

3. a dynamic thickening rolling process of controlling break of cold rolled thin strip steel is characterized in that being with near steel thickness weld seam to change by straight line or high order curve.