The rotary side-pressure stretch forming machine consists of a rotary table, stretching device, and side-pressure device. The peripheral of the rotary table is fixedly connected to a large gear, which can rotate around the center driven by a variable speed motor. The stretching part consists of a bed slide, stretching cylinder, tension arm, main cylinder clamp, and clamp height position adjustment cylinder. The side-pressure device consists of a cutting point tracking cylinder and side-pressure cylinder.
The schematic diagram shown in the figure is a principle diagram of a rotary side-pressure stretch forming machine, which consists of a rotating table, stretching device, and side-pressure device.
The rotary table 1 is installed on the vertical shaft of the base and can rotate in both forward and reverse directions driven by a motor or hydraulic motor through a worm and gear. The stretch forming die 2 and the fixed (or auxiliary) clamp 3 are installed on the table. The installation position of the stretch forming die should make the axis of the clamp tangent to the working surface of the mold at the starting position.
The stretching device consists of the bed 4, stretching cylinder 5, slide block 6, and rotating support arm 7. The bed is connected to the base of the rotary table as a whole. The double piston rods 8 of the stretching cylinder are fixed at both ends of the bed. During operation, the pistons are fixed, and the cylinder body moves. The slide block 6 is connected to the cylinder body and moves forward and backward along the rolling guide rail on the bed. The rotating support arm 7 is installed on the vertical shaft of the slide block. Another clamp 9 is installed at the front end of the support arm. The support arm 7 can rotate freely in the horizontal plane around the vertical shaft, so that the direction of the tension line is always tangent to the working surface of the stretch forming die stretching the stretch forming process.
The side-pressure device consists of the side-pressure bed 10, tracking cylinder 11, slide sleeve 12, and side-pressure cylinder 13. The side-pressure bed is parallel to the main bed of the stretch forming machine. The piston rods of the tracking cylinder are fixed at both ends of the bed, and a slide sleeve that can slide along the bed guide rail is fixed above the cylinder body. The side-pressure cylinder 13 is installed on the slide sleeve, and a side-pressure block 14 is installed at the end of its piston rod, which tracks the cutting point under the drive of the tracking cylinder.
Both clamps and the side-pressure block can be adjusted in their vertical positions along their guide plates to adapt to the installation height of different molds.
The control characteristics of the stretch forming machine tool are achieved through the closed-loop control of force, displacement, and speed using motors and hydraulic drives. The control variables, such as main tension and speed, side-pressure force, and the angle and speed of the rotary table, need to be coordinated and controlled. The key point of the stretch forming machine control system is to precisely control the various working parameters of the machine tool during the motion process to meet the requirements of force, displacement, and speed for forming.
During the operation of the stretch forming machine tool, the ends of the workpiece are first clamped on the clamps 3 and 9, and the relative positions of the two clamps are adjusted to ensure that the workpiece is tangent to the working surface of the mold at the starting position. At this time, the hydraulic valve is opened, and the workpiece is stretched by the cylinder 5. When the pre-tension reaches the yield limit of the material, the side-pressure block is pressed on the cutting point of the workpiece by the side-pressure cylinder, and then the rotary table is rotated so that the workpiece gradually bends along the mold surface under the condition of maintaining a certain value of tensile and side-pressure forces. The cylinder 5 gradually discharges the liquid from the rear chamber and moves forward under the traction of the workpiece, keeping the required tension on the workpiece. The side-pressure block is pressed on the cutting point of the workpiece until the stretch forming process is completed under the drive of the tracking cylinder 11.
During the operation of the stretch forming machine tool, first adjust the rotary table, auxiliary tension cylinder, and main tension cylinder to the appropriate positions, and adjust the horizontal positions of the main and auxiliary clamps. After the workpiece is clamped, rotate the rotary table. The auxiliary clamp wraps the workpiece around the mold. The main tension cylinder moves with the rotation of the rotary table while maintaining tension. At the same time, the side-pressure cylinder applies lateral pressure at the cutting point between the part and the mold until the workpiece is bent to the required shape. Finally, the auxiliary tension cylinder applies an appropriate supplementary tension to complete the stretching of the workpiece.