What Is Cold Rolling Mill?

Cold rolling mill is a new type of steel bar cold rolling equipment. The machine can process hot-rolled wire rods and circles with a diameter of 6.5 mm to 12 mm into cold-rolled ribbed bars with a finished specification diameter of 5 mm to 12 mm. The cold-rolled ribbed steel bar rolled by cold rolling mill is an updated product of cold drawn low-carbon steel wire in prestressed concrete members. In cast-in-situ concrete structure, it can replace grade I steel bar to save steel. It is a better kind of cold-worked steel of the same kind. If speed regulation is not required in the rolling process of the cold rolling mill, AC motor can be used; If speed regulation is required in the rolling process of the cold rolling mill, DC motor can be used.

Structure Composition:

The cold rolling mill is composed of working mechanism and transmission mechanism, in which:

① The working mechanism is composed of frame, roll, roll bearing, roll adjustment mechanism, guide device, rolling seat, etc.

② The transmission mechanism is composed of gear base, reducer, roll, connecting shaft, coupling, etc.

The gantry horizontal double active rolling mill set is composed of two active rolling mills. The installation mode and structure of the two rolling mills are the same. The main transmission part adopts the structural form of "motor → reducer → cardan shaft → rolling mill". 

The two rolling mills are horizontal rolling mills, and the rolls are installed horizontally. The rolling mill adopts gantry archway, the roll ring is sleeved on the roll spindle, and the nuts are fixed. The two ends of the roll spindle are equipped with bearing pedestal and installed in the middle of the gantry. The bearing pedestal and the gantry archway frame are installed together to fix the rolls horizontally in the middle of the gantry. 

The installation methods of the upper and lower rolls are the same. One pass reducing mill flattens the raw materials, extrudes the rib reinforcement with the crescent on both sides through the two-pass forming mill, twists the guide and adjusts the rolled piece to realize that after one pass rolling, the elliptical rolled piece is twisted by 90 ° and enters the two-pass forming mill to roll the finished reinforcement.

Working Principle:

The cold rolling mills use the motor to drag the reinforcement, and the load-bearing roll and working roll of the cold rolling mill jointly apply the force to the two surfaces of the reinforcement. By changing the gap between the two rolls, the purpose of rolling cold-rolled ribbed bars with different diameters is realized.

① Bearing roll: the bearing roll of the cold rolling mill is the roll closest to the base. When producing ribbed reinforcement, the roll plays the role of supporting the reinforcement, and evenly disperses the gravity of the reinforcement and the gravity of the work roll on the bearing roll, so as to produce ribs on the lower surface of the reinforcement.

② Work roll: the work roll of the cold rolling mill is above the load-bearing roll and is the farthest from the base. Therefore, when producing ribbed reinforcement, the roll mainly plays the role of rolling the reinforcement lifted by the load-bearing roll, so as to produce ribs on the upper surface of the reinforcement.

Maintenance:

① Check whether the electrical system of the cold rolling mill is normal before starting each shift;

② Check whether the oil level of each oil tank is normal;

③ Whether each oil filling part is filled with oil;

④ Whether the base metal feeding is reasonable;

⑤ After checking the above items;

⑥ The electrical part of the cold rolling mill should often clean up dust and sundries;

⑦ Frequently check whether the fastening of moving parts is loose and reasonable.

⑧ During the production process, the cold rolling mill shall not be used beyond the limit to avoid damage to some mechanical parts of the cold rolling mill. It shall be rolled according to the rolling standard, so as to ensure the safe use of cold rolling mill equipment and the qualification of products.

If you are interested in the cold rolling mills, please mail at marketing2@hanrm.com.

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How to Avoid Accidents in Cold Rolling?

In many steel rolling plants, especially in cold rolling production, accidents are most likely to occur, including operation accidents, equipment accidents, and quality accidents. All those directly affect equipment, quality, and output. So when accidents occur, remedies should be taken immediately.

1. The rolling piece is deviated, which usually occurs when the head is worn or the tail deviates when the belt is worn. It is caused by the uneven thickness of the incoming material, unskillful operation, old-fashioned roll holes, electrical problems, etc. The slight deviation during threading can be eliminated by timely adjusting and screwing down; for serious deviation, it is necessary to cut the strip steel in front of the frame, find out the cause of deviation, and then re-thread the strip; if it is found that the strip tail is deviated during tailing off, it is necessary to stop immediately, and lift the screw-down according to the situation to make the strip steel pass or cut it. When rolling a very thin strip, the roll is easy to be damaged due to deviation, so special attention should be paid.

　　

2. The rolling mill runout. Rolling mill runout usually occurs during high-speed rolling of extremely thin strip. Because of the beating, the thickness of the strip fluctuates, it is easy to break the strip. Therefore, once the rolling mill has obvious beating sound, the rolling speed shall be reduced immediately to eliminate the vibration. There are many reasons for the runout, such as high rolling speed, thin product thickness, low rolling pressure and small deformation of the finished pass, large tension before the strip steel, too good or too bad lubrication, insufficient roughness of the working roll, damage of the supporting roll, sudden change of various rolling parameters, large gap between the roll bearing and the bearing seat, etc. The cause of rolling mill vibration is complex and it is not easy to make a correct judgment. Through careful search and analysis, before the correct conclusion is reached, only the method of limiting rolling speed is used to prevent the occurrence of run out. 

2. The broken strip of rolled piece. There are many reasons for the broken strip of the rolled piece. Generally, it can be concluded as four kinds: defective incoming material, poor weld quality, misoperation, electrical and mechanical failure. In case of strip breaking, stop the mill immediately to reduce the loss. Serious belt breaking not only makes the work roll and even the support roll bond seriously, but also makes the treatment of the waste belt and the extraction of the work roll very difficult after bonding. Moreover, the treatment time is long and the labor intensity is large. After the belt breaking treatment, the equipment shall be inspected. The surface quality of the first coil of steel to be rolled after roll change shall be checked carefully. For the coil with weld, the mark of the weld position shall be accurate and clear. The rolling speed shall be reduced before the weld passes through the rolling mill. The steel coil with defects must be rolled slowly to minimize the occurrence of accidents in cold rolling production.

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Eight Precautions for Rolling Mills

1. Every time the rolling mill appears to be jogging, it must not exceed one second. The worm gear should be adjusted in place, and the adjustment amount should be completely equal on both sides to avoid side bends.

2. When operating the cold rolling mill, there should be a special person to guard, and there should be no phenomenon of no one to guard, so as not to find the equipment failure and not find it in time.

3. Under normal circumstances, a single cold rolling mill should not exceed 40% of the aluminum plate in a single thickness.

4. There must be no debris in the production line.

5. Adjust the amount of reduction and the number of passes according to the material of the incoming material and the capacity of the rolling mill.

6. When using a cold rolling mill, the relevant technical parameters must be in full compliance with the requirements, and it should not be operated under load.

7. Rolls should not be subjected to more serious wear and should be replaced if they are found to be worn out.

8. During the whole rolling process, if the roll affects the surface quality of the rolled piece due to wear, or the size and precision, the roll should be replaced immediately, and after the roll is replaced, the driving operation must be guaranteed 2 to 3 minutes.

Precautions of Cold Rolling Mill

1. Preparation for Startup

Let the rolling mill equipment idle for about 10 minutes. During this period, observe whether the device is running normally, and add lubricating oil and rolling oil to lubricate the equipment properly according to the regulations.

2. Precautions before Unloading

(1) The press should be raised to the specified position, the reel should be retracted into position, and the hydraulic truck should be prepared in advance for auxiliary discharge.

(2) The aluminum plate plug should be inserted into the jaws successfully, otherwise, it will be difficult to insert.

3. Some Considerations

(1) The time for each jog of the machine should not exceed one second. The turbine should be adjusted to reduce the turbine. The adjustment amount on both sides should be equal to avoid the side bend of the rolled piece.

(2) When the cold rolling mill is running, someone should be responsible for guarding to prevent problems.

(3) Generally speaking, the thickness of one rolling of a single cold rolling mill should not exceed 40% of the aluminum plate.

(4) There should be no debris in the production line.

(5) Appropriate adjustments should be made to the pass and reduction depending on the material of the incoming material and the capacity of the rolling mill.

(6) The use of cold rolling mills should meet the requirements of the main technical parameters and should not be overloaded.

(7) The mill roll should not have serious wear and should be replaced if necessary.

(8) In the rolling process, if the wear of the mill roll has affected the surface quality and dimensional accuracy of the rolled piece, the roll should be changed immediately. After changing the roller, it should idle for 2 to 3 minutes.

(9) If there is any phenomenon such as tearing or skewing of the rolled piece, the hand can not be used. It should be stopped first and then taken out.

(10) Rolled finished products or semi-finished products should be filled out with relevant records and stacked in batches.