Causes and treatment of piled steel in the rolling process of high-speed wire rod

Keyword: high-speed wire rod process

Desicription: Due to the fast rolling speed and small section size of small-size wire rod products, steel stacking accidents often occur. This paper introduces the reasons and solutions according to the classification of different rolling areas.

The production line of China SHOUGANG No. 1 Wire Rod Factory, the maximum stable rolling speed of this production line is 88m/s. The whole line is composed of 28 rolling mills, including 14 roughing and intermediate rolling mills, 4 pre-finishing rolling mills, which are arranged alternately horizontally and vertically, and the 10 finishing mills are arranged at 45° from top to bottom. Sending roll and laying machine. The product specification is φ5.5—φ16mm, the specification span is relatively large, and the varieties produced at the same time are relatively wide. Judging from the current production situation, due to the fast rolling speed and small cross-sectional size of small-sized wire products below φ6.5mm (including 6.5mm), the accident rate of steel stacking is far higher than that of other specifications. This paper introduces the reasons and solutions according to the classification of different rolling areas.

Rough and medium rolling area (1-14 racks)

The rolled piece cannot be smoothly bitten into the next sortie, resulting in stacked steel

The main causes of such accidents are:

① The front of the rolled piece is tilted after coming out of the previous sortie;

② The inverted steel at the rear of the previous one pulls up the exit guide; ③ The adjustment of the opening of the entrance guide is not appropriate;

④ Misalignment between guide and pass (rolling line is not correct);

⑤ Slot slipping;

⑥The size of the rolled piece does not meet the process requirements;

⑦ Front splitting caused by billet.

Treatment measures:

① Check the diameter and wear of the upper and lower rolls, the gap between the joints of the transmission parts, and the consistency of the height of the import and export guides for the warped head of the rolled piece;

②Reasonably adjust the entrance opening and the distance between the guide and the roller;

③ The roll gap setting of the newly replaced slot hole is too small, and the roll gap of the rolling mill should be adjusted properly or the slot hole should be re-grinded;

④ Properly adjust the roll gap of the rolling mill;

⑤ Check the blank carefully, and lengthen the length of the cutting head with 1# shear.

2.1.2 Stacked steel between the racks after the rolled piece bites

main reason:

①Incorrect setting of parameters such as rolling speed and mill rolls diameter caused by human factors;

② Improper adjustment of stacking relationship after changing rolls or slots;

③ billet temperature fluctuates too much;

④Sudden speed up or down of a rolling mill caused by electronic control;

⑤ The operator of the main console adjusts the wrong number of revolutions or shifts when adjusting the rotational speed of the rolling mill;

Treatment measures:

① Correctly set the rolling speed and roll diameter, and reasonably adjust the stacking relationship between rolling mills. Do a good job of confirmation between the two;

② Notify the heating furnace operator to adjust the fire, and at the same time keep warm and wait for rolling;

③Electrical professional inspection, empty the spare cabinet.

LMM GROUP mill rolls are made of high-quality materials, have a flawless surface finish, have appropriate hardness and are manufactured according to precise size specifications to meet the rolling characteristics and technical requirements of various rolling mills.

2.1.3 Tail stack steel after rolling (

The main reason is that at the upstream frame, when the rolled piece draws steel to cause the rear tail to break away from the upstream frame, the steel is piled up in the downstream frame.

Treatment measures: Reasonably adjust the stacking relationship and the size of the rolling mill.

2.2 Pre-finishing area (15-18 stands)

2.2.1 Stacking steel between racks

main reason:

①Incorrect setting of roll gap, roll diameter, rolling speed and other parameters;

②Guide installation is not suitable;

③Guard strikes iron;

④Coarse and medium rolling and drawing steel cause the rolled piece to be tailed after pre-finishing rolling;

⑤ Abnormal rotation speed of a certain rolling mill due to electronic control.

Treatment measures:

① Check the setting parameters again;

② Check and replace or adjust the import and export guides;

③ Adjust the height of the pre-finishing inner looper and strengthen inspection;

④Reasonably adjust the stacking relationship of the continuous rolling mill;

⑤Electrical professional inspection at the same time dump the spare cabinet.

2.2.2 A certain shift of pre-finish rolling

main reason:

①Pre-finishing cooling water pressure and lubrication system failure;

② Motor tripping;

③ The role of the accident detection system.

Treatment measures:

① Check the cooling water pressure and the control water valve beside the machine;

② Equipment professional inspection lubrication system;

③ Check whether the pre-finishing fishing line pendant is fastened, and check its proximity switch at the same time.

2.3 High-speed area (finishing mill to laying head)

2.3.1 Steel stacking between racks in the finishing mill

main reason:

① The guide wheel does not rotate or the bearing burns;

②Rolled piece start;

③Wrong installation of guide guard or roller ring;

④ Improper roll gap setting or inappropriate incoming material size;

⑤The roller ring is broken; ⑥The fishing line is broken and the rolling line is automatically broken.

Treatment measures:

① Replace the guide and guard, and at the same time strengthen the correctness of guide and guard installation;

②Strengthen blank inspection and lengthen the length of cutting head;

③Recheck and adjust the roll gap;

④Replace the roller ring and check the cooling water pipe at the same time.

⑤ Check the proximity switch at the pendant of the fishing line, and check whether there is scrap steel at the guide in the finishing mill. If there is, it means that the rear end of the previous one is stacking steel in the finishing mill, and reset the roll gap in the finishing mill.

2.3.2 Steel stacking at the scrap box of the finishing mill

Divided into two situations, one is to pile up steel without spinning, and the other is to pile up steel after spinning several circles.

The main reasons are:

① The cooling water in the water cooling section cannot be closed normally or opened too early;

② There are foreign objects in the water cooling section;

③Water-cooling channel installation dislocation;

④ After the finishing mill, the water valve of the first section of the water cooling box is too large or the water pressure is too large;

⑤ The speed matching between the finishing mill, pinch roll and laying machine is not good;

Treatment measures:

① The electric control professional checks the water valve control system and manually tests the water, and the main console adjusts the opening delay;

② Check whether the water-cooling nozzle and guide groove are installed correctly and whether there is any looseness, and check whether there is any foreign matter in it at the same time, and use a φ13mm round steel to penetrate the water-cooling section;

③ Check the speed matching between the three;

④ The specifications of the water-cooling nozzle and guide groove can be enlarged, such as replacing φ12mm with φ16mm.

2.3.3 Pile of steel at pinch roll laying head

main reason:

①Incorrect installation of the inlet and outlet conduits of the pinch roller, severe wear or foreign matter in the conduit;

②The detection signal before the pinch roller fails, so that the pinch roller cannot be opened/closed on time;

③The spinning tube is severely worn;

④ Tail clamping delay setting is too short, resulting in tail loss;

⑤ The speed mismatch between the finishing mill and the laying machine;

⑥ Internal quality defects (smelting defects) or rolling defects (severe folds or ears) of wire rods cause stacked steel.

Treatment measures:

① Check and replace the inlet and outlet conduits;

②Electrical professional inspection detection signal;

③Replace the spinning tube;

④ Lengthen the pinch delay;

⑤ Reasonably set the speed matching between the finishing mill and the laying machine;

2.4 Heap steel at the flying shear

main reason:

①The shearing speed of the flying shear does not match the speed of the upstream rolling mill, and there is a bend at the front and back of the cutting, resulting in stacked steel;

② The length of the rear tail of the flying shear is too short, resulting in the rear tail not being completely cut off and brought into the next rolling mill;

③Severe wear of the cutting edge and switch causes the cutting position to be incorrect;

④ Flying shears malfunction midway, cutting out of control.

Treatment measures:

①Reset the leading coefficient of the flying shear;

②Adjust the length of cutting head and tail;

③ Check the front guide groove of the cutting edge and flying shear;

④ Check the photoelectric cell and thermal detection signal.

2.5 pile of steel at the looper

main reason:

①The looper delay setting is incorrect;

②Inappropriate setting of looper height;

③The set roller, guide roller or guide plate of the looper is seriously worn;

④ Looper scanner failure;

⑤The front thermal detection signal is blocked;

⑥ Excessive water mist or sunlight will affect the inspection results.

Treatment measures:

①Reset or adjust parameters;

②Replace the process spare parts, or repair the guide plate;

③ Replace the looper scanner and re-adjust the zero position;

④Add a fog blower to the place where there is a lot of water mist, and add a shielding board at a suitable angle for the sunlight.

In the production process, when a steel pile accident occurs, due to the limitation of time and indicators, it is necessary to find the cause quickly and accurately. This requires a comprehensive consideration of the accident that occurred and multiple reasons to find the cause, so as to shorten the processing time and avoid repetition. Sexual accidents happen. It also requires on-site operators to continuously and regularly check the size of the rolled piece, the relationship between the stacking and pulling of the rolling mill, and the situation of guides and guards in daily production, so as to better reduce the frequency of accidents.