According to the technical characteristics of ultra-slender long-axis turning, the following measures are taken when processing the work roll of 40×21000 ultra-large CNC marine plate rolling machine.
Increased rigidity of extra-long rollers
Improve the clamping method of the workpiece, using one clamp and one top, as shown in the figure.
On the basis of the traditional one-clamp-one-top clamping, an open traveler is placed between the jaws and the super long roller of the marine plate bending machine to reduce the axial contact length between the jaws and the super long roller of the marine plate bending machine, and eliminate Over-positioning during installation can reduce bending deformation; at the same time, the top should adopt elastic live top, so that the super-long roller of the marine plate rolling machine can be freely extended after being heated, reducing its bending deformation when heated.
Chuck, steady frame, work roll, tool, positioning support sleeve, center
It is supported by a center frame and an auxiliary adjustable positioning support sleeve. It is supported by the center frame and the auxiliary adjustable positioning support sleeve, which can move on the lathe guide rail, so that it can be adjusted at any time during the processing. As shown in the figure, it is equivalent to adding one or two auxiliary adjustable supports on the slender shaft. , which increases the rigidity of the slender shaft, which can effectively reduce the influence of radial cutting force on the slender shaft. By adjusting the auxiliary adjustable positioning support sleeve, the contact state between the bracket and the workpiece can be improved to be the best, and it is stable during turning and is not easy to generate vibration.
Reduce the influence of cutting force and cutting heat
Turning super long rolls of marine plate rolling machine by reverse cutting method. The reverse cutting method means that during the turning process of the slender shaft, the turning tool is fed from the spindle chuck to the tailstock direction, as shown in the figure. In this way, the axial cutting force generated during processing makes the slender shaft tensioned, eliminating the bending deformation caused by the axial cutting force. At the same time, the elastic tailstock tip can effectively compensate the compression deformation and thermal elongation of the workpiece from the tool to the tailstock, and avoid the bending deformation of the workpiece
Reasonably choose the geometric parameters of the cutting tool
The super-long roll of the marine plate rolling machine adopts the processing procedures of rough turning, semi-finishing turning, and finishing turning. Reasonable tools should be selected for each process, as shown in Figure 6. Improper selection of tool geometry parameters will cause excessive cutting force, bending deformation of the roll shaft, and poor surface quality.
Leading angle
The size of the main deflection angle directly affects the proportional distribution relationship between the back force and the feed force that causes the bending deformation of the slender shaft. As the entering angle increases, the feed force increases, while the back force decreases. When reverse cutting is used, the feed force is increased, which strengthens the tensile effect of the workpiece; the back force is reduced, which reduces the bending deformation and vibration of the slender shaft, both of which are conducive to improving machining accuracy. When the super long roll of the plate rolling machine is used for vehicles and ships, the main deflection angle of the rough car is 45°, and the main deflection angle of the fine car is 75°.
Blade inclination
The influence of the inclination angle on the feed force and the back force tends to be the same as that of the entering angle. When rough turning, the blade inclination angle is -2° to increase the impact resistance of the blade; when finishing turning is 2°, the chips are discharged to the surface to be processed, and the tool is easy to cut into the workpiece, reducing the cutting force and preventing chipping.
Front angle
The increased rake angle makes the cutting edge of the tool sharp, which can reduce the cutting force and cutting heat. According to the selection principle of the rake angle, select 25°.
Rear angle
Generally, a large amount of feed is used, and at the same time it is a powerful cutting, and the cutting heat is high. In order to increase the durability of the tool, a smaller relief angle is selected, taking 5°.
Tool nose radius
The radius of the tool nose arc increases and the feed force decreases. In order to prevent vibration, a smaller tool nose radius should be selected.
| Type | Leading angle | Blade inclination | Front angle | Rear angle | Tool nose radius |
| Rough turning tool | 45° | -2° | 25° | 5° | 0. 5mm |
| Finishing tool | 75° | 2° | 25° | 5° | 0. 3mm |
Choose the right amount of cutting
Improper selection of tool cutting amount will cause excessive cutting force, bending deformation, and poor surface quality. Under the premise of as large a feed rate as possible, increase the cutting speed and back-cutting amount as much as possible.
| Type | Feed/(mm/r) | Spindle speed/(r/min) | Back cut/mm |
| Rough turning | 0. 5 ~ 0. 6 | 30 ~ 40 | 10 ~ 15 |
| Half finishing tool | 0. 3 ~ 0. 5 | 30 ~ 40 | 3 ~ 5 |
| Finishing tool | 0. 25 ~ 0. 4 | 30 ~ 50 | 0. 8 ~ 1. 2 |
Improved geometry accuracy, surface roughness
The processing technology of the super-long roll of the marine plate rolling machine adopts the center frame and the auxiliary adjustable positioning support sleeve to support the workpiece. During the segmental processing of the workpiece, it causes multiple tool changes and tool setting, so that there are traces of tool connection, which affects the roughness of the surface. Spend. For this reason, the self-made polishing wheel is used to polish the surface of the roller after finishing, which solves the super long roller joint knife mark of the marine plate rolling machine and improves the surface roughness. Figure is a picture of the polishing wheel, and Figure 8 is a comparison picture before and after polishing of the ultra-long roll of the marine plate bending machine.
Research results
Through the research on the manufacturing technology of the super long roll of the marine plate rolling machine, a series of effective measures are adopted to make the processed super long roll of the marine plate rolling machine have a surface roughness above Ra3.2, an ellipticity of 0.05mm, and a circular runout of 0.15 mm, and the work efficiency is greatly improved, which fully meets the requirements of this project. The processed super long roller is shown in Figure 9
Conclusion
Through the analysis of the processing characteristics of the ultra-long roll, measures such as increasing the rigidity of the ultra-long roll, reducing the influence of cutting force and cutting heat, rationally selecting the geometric parameters of the tool and selecting the appropriate cutting amount, etc., make the processing of the ultra-long roll The quality has been greatly improved, the processing requirements have been met, the manufacturing efficiency of key parts has been improved, and good benefits have been achieved.