Current status of profile bending machines
Most of the high-end Profile Bending Machines/Section Bending Machines in China adopt the Double-Pinch form, which is mainly composed of upper rollers, lower rollers, guide rollers, and frame parts. It is worth noting that the two lower rollers can move up and down in an arc around the central axis under the drive of the hydraulic motor.
The guide roller is installed on both sides of the upper roller on the machine tool, and it can move vertically and horizontally. In order to better improve the rolling precision, such as curve the angle iron, BIT’s PBH Profile Bending Machines adopt the 3D guide rollers, and the direction of movement is up and down, left and right, and forward and backward.
Read More: Profile Bending Machine: 5 Things Before Buy, 6 Steps to Bend
The 3 rollers of the profile bending machine(3-roll bending machine, Read More: Best Buyer’s Guide for 3 Roll Bending Machine) are all main drive rollers, with simple structures and accurate forming. However, due to the overall structure of the frame, this type of structure is only suitable for small and medium-sized profile bending machines due to the restrictions on the overall size of the machine due to installation and transportation, which restricts the development of profile bending machines in the direction of large-scale and heavy-duty. At present, the maximum bending section modulus of this kind of structural profile bending machine in the world does not exceed 1750cm3.
Variable Geometry Profile Bending Machine
With the rapid development of China’s economy, it is necessary to build large-scale indoor event venues with large spans and large activity spaces. Large structural steel beams need to be bent for infrastructure construction such as large international airports and high-speed rail station waiting rooms. For this reason, China’s technicians innovatively designed the traditional arc downward adjustment structure of the profile bending machine, and successfully developed a large profile bending machine with a section modulus as high as 5500cm3.
This profile bending machine/section bending machine adopts a variable geometry structure (Read More: 3 Roll Variable Geometry Plate Bending Machine – PRV), the section modulus of section bending is 5500cm3, and the maximum can reach 10000cm3, which effectively solves the high-precision and high-efficiency curving of large-scale profiles.
Structure overview
The variable geometry profile bending machine is mainly composed of upper and lower roll frames, upper and lower rolls, guide rolls, connecting beams, bending dies, hydraulic pressure, electrical and other parts
The variable geometry profile bending machine is a three-roller bending machine with an adjustable center distance between the lower rollers. The installation method is vertical installation, that is, the three main shafts are perpendicular to the ground. The upper roller can be arranged symmetrically or asymmetrically with respect to the two lower rollers and can move up and down under the drive of the hydraulic motor to provide a pressing force for profile rolling. The distance between the centers of the two lower rollers is adjustable, and its horizontal movement is driven by a hydraulic cylinder. The two lower rollers are the main drive spokes, which are driven by sub-rollers, and are independently driven by hydraulic motors and reducers. The lifting movement of the guide roller is driven by a hydraulic cylinder.
Note: The significant difference between the variable geometry three-roller bending machine and the Double-Pinch 3-roll bending machine is that the upper roller of the variable geometry three-roller bending machine can move up and down, and the lower roller can move horizontally left and right; Double-Pinch 3-roll bending machine, the upper roller is fixed, and the lower roller moves up and down in an arc.
Upper Roller
The upper roller part is mainly composed of the upper roller oil cylinder, dumping oil cylinder, dumping side bearing body, fixed side bearing body, upper roller mold, and other parts. Driven by the upper roller cylinder, the upper roller guide frame, the bearing body installed on it, and the upper roller mold can move back and forth in the upper roller frame body to provide downward pressure for the bending of the profile. The dumping oil cylinder drives the dumping side-bearing body to turn over. It is easy to replace the mold and discharge the material. The upper roller adopts self-aligning spoke bearings, which can be used as passive rollers for rotary motion.
Lower roll part
The lower roller part is mainly composed of the lower roller moving frame, the lower roller mold, the lower roll moving oil cylinder, and the lower roller transmission device. Driven by the lower roller oil cylinder, the center distance between the two lower rollers can be adjusted to meet the needs of curving different profiles. According to the requirements, the two lower rollers are active work rollers, which adopt the structural form of split roll drive, and are respectively driven by a hydraulic motor and driven by a planetary reducer through a first-stage gear.
6 advantages of variable geometry profile bending machine
- Advantage 1#: The variable geometry structure is adopted on the large profile bending machine. When the bending section modulus of the profile is large and the bending radius is large, a larger center distance is used to reduce the force, and bending torque when the profile is bent; when the section modulus of the profile is small and the bending radius is small, a smaller center distance is used. to reduce the length of the remaining straight sides. At the same time, the upper roller and the lower roller can also be arranged asymmetrically to realize the pre-bending of the end of the profile, broaden the scope of use of the machine, and improve the force of the machine.
- Advantage 2#: The upper and lower three spindles of the traditional profile bending machine are generally cantilever types. For extra-large profile bending machines, due to the large force on the spindle, the rigidity of the cantilever type installation spindle cannot be guaranteed. In the variable geometry design, the cantilever type is changed to For double point support. The supporting part adopts heavy-duty double-row self-aligning spoke bearings to reduce friction loss during the bending process of the profile. In this structure, the force on the three main shafts is reasonable to ensure that the stiffness of the main shaft meets the design requirements.
- Advantage 3#: The upper roll frame and the lower roll frame of the machine are relatively independent, connected by connecting beams and pin shafts, which not only meets the requirements of the strength, rigidity and running accuracy of the whole machine, but also facilitates installation and transportation.
- Advantage 4#: The two lower rollers adopt the structure type driven independently by separate rollers, and a planetary reducer and a first-stage gear drive are respectively driven by hydraulic motors. The independent drive of the sub-rolls can eliminate the movement interference phenomenon between the rolls, reasonably distribute the transmission torque, and reduce the resulting mold wear problems. The hydraulic transmission makes the movement stable and has overload protection capability, and the planetary gear transmission makes the machine compact in structure and high in transmission efficiency.
- Advantage 5#: Add an additional guide roller mold device whose movement direction is parallel to the bending axis of the profile to restrict the flow of the profile and achieve a certain shape of space bending.
- Advantage 6#: Conducted in-depth research on the elastic-plastic deformation theory of profiles in the bending process, deduced calculation formulas for the strength, stiffness, contact stress, and main drive power of key parts of the machine, and established the bending process parameters of profiles And the mathematical model including the geometric position relationship of the main shaft, the die diameter, the working spoke and the motion feed amount has laid the foundation for the optimal design of the machine and the programming of the control system.
Final words
It is a relatively ideal structure type to adopt variable geometry structure type on large-scale profile bending machine, and it is a bold breakthrough to the traditional structure.
The variable geometry profile bending machine has novel and reasonable structure, safe and reliable performance, simple manufacturing process, and convenient installation, maintenance and transportation.