Q1. What are the requirements of the rolling mill for incoming cold-rolled sheets?
answer:
1) The chemical composition of steel should comply with the provisions of national standards.
2) The thickness and width of incoming materials meet the regulations.
3) There is no iron oxide scale on the surface and no cracks on the edge.
4) No defects such as stripe scratches, embossing, embossing, blisters, and delamination.
5) The strip has no tower shape, loose coil, etc.
Q2. What are the main shape defects of the cold-rolled strips?
Answer: “Scythe Bend”, “Wave Shape”, “Lady Bend”. There are many types of waves, such as one-sided waves, two-sided waves, intermediate waves, two-sided waves, periodic waves, and partial waves.
Q3. What effect does the flatness defect have on the cold rolling process?
Answer: The bad shape of the plate has a great influence on the cold rolling process, which brings difficulties to the actual operation. The severe camber will cause the belt to run off track and break the belt, and the wave shape will lead to the accident of strangling the roll and breaking the belt, and the shape of the plate is not in good condition. The increase in speed is limited, thus affecting the mill capacity, and the poor shape of the rolling mill also limits the minimum thickness that the mill can roll out.
Q4. What kinds of shape adjustments are there in this rolling mill unit?
A: Bending roller adjustment, emulsion adjustment, intermediate roller movement adjustment, and pressing swing adjustment.
Q5. How many ways are there to observe and measure the plate shape during rolling?
Answer: Visual inspection method, induction method (beating both sides of the strip with a wooden stick), and measuring with a tension roller shape meter.
Q6. What are the ways to adjust the thickness of the cold-rolled strips?
Answer: Use the rolling force P to indirectly measure the thickness of the rolled piece, and then adjust the roll gap to control the thickness, which is called pressure-thickness control (P-AGC).
Q7. What is the function of the cooling system of the rolling mill process?
answer:
1) Cool the rolls. During the rolling process, due to the deformation of the metal and the friction between the metal and the roll, a large amount of deformation heat and friction heat is generated, which increases the temperature of the roll and the rolling piece, and the emulsion plays a cooling role.
2) Lubrication. Reduce the friction between the strip and the roll, so as to reduce the deformation resistance of the metal and reduce the rolling pressure.
3) Adjust the shape of the plate. In the rolling process, the flow rate of each section of the emulsion spray beam can be adjusted to control and improve the shape of the plate.
Q8. Briefly explain the role of the emulsion in the rolling process.
Answer: The emulsion mainly plays the role of lubricating and cooling in the rolling process. During the rolling process, due to the contact between the roll and the strip, the rolling pressure is large. In order to eliminate this effect, the friction between the roll and the strip is reduced by the emulsion, thereby reducing the rolling pressure and controlling the shape of the strip. Another function of the emulsion is to cool the strip and the roll. During the rolling process, the contact between the roll and the strip generates heat, which causes the thermal expansion of the roll. The thermal expansion of the roll is eliminated by the emulsion, so as to achieve the purpose of controlling the shape of the plate.
Q9. What is the spray angle between the emulsion and the surface of the strip? What are the principles of angle selection?
Answer: The spray angle of the emulsion of the work roll is generally 45° or 60°. The principle is that the coolant should be sprayed on the roll gap and the strip to the greatest extent, so as to cool the roll and reduce the friction between the roll gap and the strip. effect.
Q10. How to adjust the emulsion flow of the work roll and intermediate roll?
Answer: In actual production, according to the actual plate type, the main operator converts the operation signal into a pressure signal by adjusting the potentiometer knob, and adjusting the opening amount of the pneumatic membrane valve in the pipeline, so as to achieve the purpose of controlling the flow of the emulsion.
