Bending machine parameters and working principleRelease Time : 2021-01-06 View Count : 次
Process principle and characteristics of plate rolling machine
The plate rolling machine is a general equipment for rolling metal sheets into cylindrical, arc or other shapes. Equipped with auxiliary devices, it can also roll conical and elliptical workpieces. Widely used in boiler, shipbuilding, petroleum, chemical, hydraulic, metal structure and other machinery manufacturing industries
The principle of three-point fixed circle, using the relative position change and rotation of the work rolls, the plate is sent to the people, and the upper or lower roll is moved strongly to cause the plate to be plastically deformed and bent. The work roll is driven to rotate. Due to the friction between the working surface and the bent sheet, the sheet can be bent along its longitudinal direction. The plates sequentially obtain plastic bending deformations with the same curvature.
Adjusting the relative position of the work rolls can obtain different bending radii. The maximum bending deformation of the plate each time it passes the work roll is limited by the biting force. For workpieces with small R/t, the relative position of the work rolls must be adjusted several times to make the plate pass through the roll shaft several times.
In fact, the minimum bending radius is not only limited by the upper roller shaft diameter and springback, but also by the rigidity of the roller shaft, the power of the machine, and the cold work hardening of the metal. For steel plates whose relative plate thickness (the ratio of plate thickness to twice the bending radius, ie t/2R) is greater than 3%, hot bending is usually used.
The type and basic parameters of the rolling machine
Type of rolling machine
Divided into four types
1. Symmetrical three-roller bending machine
Symmetrical arrangement. The upper roller can move up and down, and the center distance of the lower roller is fixed. Therefore, there is a straight part at both ends of the plate, that is, the remaining straight side, the length is about half of the center distance between the two lower rollers. Before the cylindrical parts are rolled and bent, special equipment and molds are used to pre-bend the ends of the plates.
2. Asymmetric three-roller bending machine
The work roll is characterized by asymmetrical configuration. The vertical plane formed by the axis of the lower work roll has a small offset distance relative to the vertical plane formed by the axis of the upper work roll, and the lower work roll can be raised and lowered vertically. The upper and lower work rolls are active rolls, and the side work rolls are passive rolls, which can be tilted up and down along the guide rail plane at a certain angle relative to the vertical plane. When working, the plate ends before or behind the clamping points of the upper and lower rolls are very short, and the remaining straight edges are generally only twice the nominal coil thickness. Almost all the plate ends can be bent, and the plate ends do not need to be pre-bent by other methods. . In addition, the allowable degree of bending deformation per pass through the work roll is larger, and the bending efficiency is higher.
3 Down-adjusting three-roller bending machine
3c) Curved downward adjustment type three-roller bending machine 3d) Horizontal downward adjustment type three-roller bending machine
l) The vertical downward adjustment type and the inclined downward adjustment type three-roller plate bending machine are similar in type. The upper roller rotates fixedly, but the movement tracks of the two lower rollers are different. One is vertical movement and the other is inclined movement.
2) The arc downward adjustment type three-roller plate bending machine is a new type of integrated vertical downward adjustment and inclined downward adjustment. The upper roller is fixed for rotation only
3) The upper roller of the horizontally downward-adjustable three-roller bending machine can move up and down, and the two lower rollers can move horizontally independently or at the same time. The three working rollers are all active rollers, so there is no slippage when the plate is rolled. Especially when the thin plate is rolled, it is more remarkable. The adjustable strokes of the two lower rollers are relatively large. During the bending process, each lower roller performs the functions of the lower roller and the side roller in turn, that is, two asymmetric three-roller plate bending machines are formed successively, and the workpiece is loaded and unloaded at one time. It can complete all bending work including front and rear extremes.
4. Four-roller bending machine
The four-roller bending machine has an upper roller, a lower roller and two side rollers. There are two main types: side roller tilt adjustment type and side roller arc adjustment type. The upper roller is fixed and rotating, and when one of the two side rollers is adjusted upward respectively, a downward adjustment type asymmetric three-roller plate rolling machine is formed. When bending thicker plates, the work rolls can also work in a symmetrical arrangement. Therefore, it can be regarded as a composite of symmetrical and asymmetrical three-roller bending machine. The four-roller bending machine can roughly level metal sheets. At the same time, adjust the tilt of the rollers on both sides; the cone can be easily rolled. When pre-bending and rewinding the plate, it can be formed at one time without turning around, and the remaining straight edges of the pre-bent plate are small. The structure of the four-roller bending machine is complex and heavy, and the cost is also high
The structure of the rolling machine
The common components of the bending machine structure include: frame, work roll, main drive, auxiliary drive, control, lubrication and other accessories.
The frame and base are welded by casting or steel plate, and the work rolls are quenched and tempered with high quality medium carbon steel. Both ends of the work roll are supported by composite sliding bearings, friction coefficient <=0.04, and a tilting mechanism is installed on the transmission side of the machine. Most of the small and medium-sized plate rolling machines use manual tilting and tilting mechanisms; large plate rolling machines, more Hydraulically driven tilting mechanism
Figure 5-5-3 Hydraulic drive tilting mechanism
The dumping bearing body mechanism is installed on the other side, and the dumping mechanism is hydraulically driven
Figure 5-5-4 Hydraulic driven dumping mechanism
The butterfly spring balance mechanism adopted in recent years is shown in Figure 5-5-5. Both the tilting mechanism on the transmission side and the dumping mechanism for the bearing on the discharge side facilitate the unloading of the rolled cylindrical workpiece. The tilting mechanism can tilt the bearing body 85-900, and the tilting mechanism can tilt the upper work roll by 1-3O;
8-adjusting nut 9-frame
Symmetrical and asymmetrical three-roller bending machine
The upper roll of the symmetrical bending machine is thick and the lower roll is thin. For machines with wider sheets, the supporting rollers are added to increase the rigidity of the lower rollers. The two lower rollers are the main driving rollers. In order to realize the lifting of the upper roller, a sliding guide rail and a lubricating device perpendicular to the base are arranged on the frame. It only needs to be equipped with pre-bending equipment or tooling to meet the bending and forming of different workpieces. Therefore, the symmetrical three-roller plate bending machine is widely used. The diameter of the upper and lower rolls of asymmetrical plate rolling machines are generally equal, and the diameter of the side rolls is slightly smaller. Up and down are active, and side rollers are passive. In order to realize the lifting of the lower roller and the side roller, a sliding guide rail and a lubricating device that are inclined to a certain angle perpendicular to the base and the base are installed on the frame at the same time, and the structure is more complicated. When bending the end of the plate, the plate needs to be turned around, which limits the development and adapts to medium and small machines.
Down adjustment three-roller plate bending machine
1) Horizontal downward adjustment type three-roller bending machine
Changzhi Forging Machine Tool Works W11xCNC-140x4000 Horizontal Down-adjusting Three-roller Plate Bending Machine
4-lower roller drive 5-machine base 6-upper roller drive
Horizontal structure. The upper roller is connected with the piston rod of the main hydraulic cylinder on the base by the bearing bodies at both ends, and the lower roller is installed on the integral seat together with the left and right frames that move horizontally. One end of the machine is equipped with a dumping mechanism, and the other end is equipped with a transmission system of three work rolls and a butterfly spring balance mechanism.
Upper roller lifting
1- rolling bearing body 2- upper roller 3- base and main hydraulic cylinder
The horizontal movement of the lower roller and the tilting of the bearing body are hydraulically driven, the upper roller is mechanically driven, and the lower roller is hydraulically driven.
The horizontal movement mechanism of the lower roller realizes the horizontal movement of the front and rear lower rollers separately or at the same time through the liquid positive drive. In order to make the generatrix of the workpiece parallel to the axis of the work roll during feeding, a centering groove is opened on the lower roll body, which is simple and practical.
The rotary motion of the upper roller is driven by four electric motors through planetary gear reducers. The transmission system is installed inside and outside the steel plate welded box and moves up and down along the frame together with the upper roller.
The rotary movement of the lower roller is realized by a hydraulic motor driving a planetary gear reducer,
1- Lower roller 2- Hydraulic motor 3- Planetary reducer
The transmission system is installed on the frame supporting the lower roller and moves horizontally with the lower roller moving mechanism. Hydraulic brakes are installed in the high-speed stage of the upper and lower roller drive systems
Three-roller bending machine
The main drive system is driven by a motor through a multi-stage double arc gear to rotate the two lower rollers, and a chain drive drives the upper roller to rotate. In order to match the linear speed in the process of up and down bending the workpiece, an instantaneous sliding device is provided in the chain drive mechanism. In order to achieve accurate positioning when pre-bending the plate, expansion and contraction brakes are set in the high-speed stage of the transmission system. Since the three work rolls are all active rolls, it avoids slipping when bending small diameters and bending thin plates.
The auxiliary drive system is supplied by the hydraulic pump station, and the lower roller is raised and lowered in an arc, the tilting side bearing body is erected and tilted through the implementation of the valve group, and the turning and resetting of the feeding device is adjusted.
Lower roller arc lifting mechanism
1-Hydraulic cylinder 2-Fixed shaft 3-Roll 4-Rotating arm
The swing hydraulic cylinder has a large load-bearing capacity, and its volume can be reduced by 1/4 compared with the tilt-down lifting hydraulic cylinder of the same specification. In order to ensure the accuracy of the machine, the boom is required to have sufficient strength and rigidity. The rotating arm of the small coiling machine adopts Q235-A plate welding and aging treatment after welding; the large and medium-sized coiling machine adopts ZG310——570 material casting and quenching and tempering treatment, and the upper roller balance mechanism adopts the upper pressure type, its function is to ensure After the tilting side bearing body falls, the upper roller is in a horizontal state. The mechanism consists of bearing bushes and rolling bearings. Adjust the composition of the screw rod and the locking screw.
On the dumping side, the roll end is equipped with a conical workpiece device, which is composed of a sleeve, rolling and sliding bearings, positioning keys, friction blocks, etc. Since the tapered workpiece is unfolded in a fan shape, only the small end needs to be close to the friction block to decelerate during bending, and the linear speed is fast at the large end and slow at the small end, and it can be easily rolled into a cone.
Four-roller bending machine
Sliding guide grooves for upper and lower work rolls and side work rolls are arranged in the frame, and the work rolls are driven by hydraulic pressure to make linear displacement in the guide grooves. The upper roller and the lower roller are both active rollers, which are usually driven by a hydraulic motor through a planetary reducer. Computer-controlled four-roller plate bending machine
The diameter of the upper roller of the four-roller bending machine is larger, the diameter of the lower roller is generally slightly smaller than or equal to that of the upper roller, and the diameter of the side roller is smaller than that of the upper roller. The work roll is made of high-quality carbon structural steel, quenched and tempered, and alloy structural steel is used when there are special requirements. In recent years, the upper roller has also been made into a waist drum shape.
The four-roller plate rolling machine has a closed frame and an open frame, which are welded by Q235-A ordinary carbon steel plate and are annealed after welding. Cast steel structure is used for mass production. The support roller device is installed in the middle of the lower roller of the large and medium-sized four-roller bending machine to increase the support force of the lower roller when pre-bending the end of the plate and compensate for the bending deformation of the lower roller. The support roller is set on the hydraulic cylinder and is hydraulically controlled. Drive to realize the adjustment of supporting force. The lifting of the work roll adopts hydraulic or mechanical drive
1-upper roller 2-side roller 3-lower roller 4-tilting bearing 5-frame 6-lower roller drive 7-upper roller drive
Sliding or rolling bearings are installed at both ends of the work roll, and the lower part has an arc structure to adapt to the tilting and lifting of the work roll.