Operator of the plate roller
The operator must be familiar with the structure and operation of the roll bending machine, and then the equipment manager will be qualified to carry out the roll operation of the rolling machine.
The rolling process must arrange for two people to be operated at the same time, a person is responsible for the overall coordination, another person is to assist workers, and two people must cooperate with a tacit understanding in order to finish the rolling process of the cylinder.
Preparation of plate rolling machine
Before use, check whether the plate rolling machine is in good condition after startup check whether the hydraulic system pressure is normal, and the overturned side can be normally closed, when starting the machine the bottom roller of the plate rolls is under normal rotation, to ensure the system operating normally before using.
Commissioning plate rolls
To adjust both the upper roller and bottom roller to the parallel state by visual inspection. Adjust the center distance to the proper distance according to the parameters of the rollers.
Steel Sheet
The parameters of the steel sheet
The yield limit of the steel plate, the minimum allowed rolling diameter, the width of the steel plate, and the thickness of the steel plate shall be allowed within the parameters of the rolling machine.
Steel plate surface quality
The cutting edge of the plate shall not have obvious defects, and the surface of the steel plate shall be clean, flat, free of starting layer and scratches, etc.
Heat treatment of the steel plate before the roll
For example, for 45 # steel, the whole plate must be annealed before rolling, and the low carbon steel shall not be heat treated.
Plate bending process
Feed
Place the steel sheet plate for rolling on the plate bending machine, and adjust the upper roller edge paralyzed with the cutting edge of the plate with the visual method, and the error control in the range of ±0.5mm.
Pre-bending
On the basis of the contact surface for the upper roller outer circle and plate, press 15mm continuously. Jog control to rotate the bottom roller, when the plate arc length reaches 600-800mm, stop the rotation. Again press the upper roller for 10mm, rotate the bottom roller, and stop it when the end of the steel sheet tangent to the bottom roller. Repeat press upper roller, rotate bottom roller until the pre-bending sheet arc basically consistent with the sample.
The preserving circular arc should transit to the straight edge, do not allow the dead bending phenomenon, and avoid causing subsequent difficulty in roundness correction.
The other end of the steel sheet plate adopts the same method for pre-bending.
Circular rolling with pre-bending
Pre-bending rolling
On the basis of contacting plate surface for upper roller, press 15mm continuously, jog rotate the bottom roller. The continuous rotation of the bottom roller can be carried out after confirming all the rollers function well.
Note: at this procedure, continuously gear start bottom roller is not allowed, preventing accidents.
In the process of rolling, operators must focus their attention when starting the rolling machine. However, the assisting operator, must timely and accurate command and cooperate with the main operator when there is a visual blind area for the rolling machine control.
To roll circular by pressing the upper roller repeatedly. When the distance between the two ends of the plate reaches 800mm, reduce the pressing pressure of the upper roller, and drop to 3-5mm each time until the two ends are close together.
During the circle rolling process, to observe whether the plate for rolling is offset, and when the offset (visual) exceeds 10mm, stop the rolling process and reduce the error.
Solution: Lift the upper roller 30mm, when the steel cylinder material is completely loose, move the plate in the opposite direction, and then push the bottom to press the upper roller to the original position, then continue to roll the circle.
Edge alignment and spot welding: generally, the edge of the cylinder will not be aligned.
The solution: life the upper roller 5 mm, place one 3mm sheet steel mat under the offset position which contact with the bottom roller, jog control the bottom roller to move the pad into the place between the plate and bottom roller. Press the upper roller for 3-5mm, to make the left and right migration move toward the alignment direction.
Properly jog control the bottom roller to align the circular surface (measured by sample or ruler). After confirming qualified, spot welding the corresponding position. The spot weld shall not be allowed to be defective, the spot welding position should be strong and effective.
Circular rolling without pre-bending
Plate rolling machine operation procedure and method Plate rolling machine operation procedure and method
The rolling process is the same as above rolling with pre-bending. The whole roll circle process cannot have an obvious dead bending phenomenon. When the two ends of the plate are closed, make sure the two straight edges are straight or slightly inward (concave≤10mm) before spot welding.
Welding
Mild steel, such as Q235A, generally adopts the CO2 gas shielded welding machine, welding must be carried out on the weld gouging and weld well, the weld joint surface should be less than 3 mm, and the weld joint residual height should be uniform. If the height exceeds the standard, remove the height by sanding process, to make it less than 3 mm, weld uninformed. The weld joint should have no surface defects.
Medium carbon steel: for example, 45 #, after preheating welding, must be rounded and must be annealed after welding. The rolling and welding method is the same as low carbon steel.
Special materials: execute according to a specific process.
Roundness correction
First, put the finished welding cylinder on the plate bending rolls, overturned the side roller, align the cylinder center and make it parallel to the center line of the plate rolls roller. Besides, put the cylinder in the center of the rolling machine to receive the hydraulic pressure evenly.
Before roundness correction of non-pre bending, the flat parts should be rolled back and forth separately, the press distance is 3-5mm each time until the roundness is consistent with the sample by a visual method.
Roll the cylinder welding joint to the bottom, and adjust the upper roller downward to make it in contact with the cylinder. Then lower the upper roller slowly and roll back and forth, starting with lower pressure generally no more than 15mm, and the subsequent cylinder will not exceed 10mm per roll.
(refer to press distance of the cylinder for one cycle rolling = diameter * plate thickness / 10000).
The maximum lower distance of the upper roller of the circle correction(refer to the maximum pressure of the cylinder = diameter * plate thickness / 3000) can be appropriately increased or decreased with the actual need, generally not exceeding 20% of the reference value.
When the lower distance reaches the perfect condition, roll 5 more circles to make the stress basically even. Then measure the inner circle’s roundness at a place lower than the horizontal diameter.
Down the amount in place after the roll around five laps, to stress the cylinder evenly basic, and adopts the measure cylinder diameter circle by level lower (clockwise 7-8 or 4-5 for hour pointer).
If the roundness of the cylinder basically the same after measuring the whole circle, then the upper roller can be lifted.
Lift the upper roller: in principle, the upper roller should be moved slowly, and the increase of each turn shall not be greater than 5mm, generally 2-3mm. After 3-4 times turn, to make the upper roller don’t contact the cylinder anymore.
Measuring the roundness with a tape measure, the roundness is generally less than 10mm, which can be considered to be qualified, and the subsequent need for artificial circle correction to meet the requirements of the drawing.
Artificial roundness correction
In general, the flame heating method is used to make the roundness correction. Before the roundness correction, use the sample or the tape measure to mark the maximum and the minimum size as well as the arc position. The mark is accurate and obvious.
For circular arc and size unqualified position, heat with flame, generally thick plate with large electrical flame heating, when the heat quickly reach about 600-700 ℃ (such as low carbon steel Q235), take a point or linear heating, make the steel plate produces a temperature difference in the thickness direction, to generate local deformation to achieve roundness correction purpose.
After the heating position is cooled, measure with a sample and tape measure, for those place which is not qualified, the artificial circular correction method should be adopted, to make it conform to the requirement of drawing.
Things to watch out for when using the plate rolling machine
- The plate bending machine must have someone responsible for management.
- The operator must be familiar with the structure and performance of the plate bending machine and the method of use. Only after the agreement of the responsible management personnel can the operation be performed.
- Before starting up, check carefully whether the safety device is in good condition.
- During operation, hands and feet should not be placed on rollers and transmission parts, and workpieces.
- After the work is interrupted, the clutch should be brought to neutral.
- It is forbidden to overload the work plate bending machine.
- The tilting of the upper roll lift bearing and the balancing of the upper roll must be performed after the main drive is stopped.