Design and Fabrication of Bending Machine
Introduction Bending Machine
We need different types of parts to be bent for different work. The available machines are costly and bulky. However, there are some manual machines too but they require too much force to be applied to bend the component. Drawbacks of these machines are lack accuracy, low productivity and thus resulting in severe fatigue in the operator.
There are different types of bending machines. They are classified as below:
- Bar bending
- Channel Bending
- Rod/ pipe bending
- Square bending
The most famous forming roller method for bending is recommended for all large bends, where the centreline radius is at least 4 times the OD of the tube. This type can be successfully employed for bending pipes or heavy wall tubing to a smaller radius.
This operation is involved with the fact of “spring back” action of some materials after being formed. It is often necessary to use a radius collar which will be having a smaller diameter than that of the circle required for its compensation. Actual size can be determined by doing experiments, as “spring back” varies with different materials.
The same general bending rules which cover forming of the channel with “flanges out” also apply when it is formed with “flanges in”. Since it is necessary to compress the flanges as they bend inwards, the operation shown below requires more bending pressure than when forming with “flanges out” and it is recommended that the largest possible radius be used to allow for compression of the material.
Construction of Bending Machine
A hydraulic jack with a semi-circular pulley at its front end is fixed on the frame in between two pulleys and below it by calculating the working distance. There is a provision for adjustment of the jack so that any type of shape and curvature can be achieved.
A flat platform is formed on the top of the base structure. Two mounting points are fixed on this platform. During the working of the machine, these points are exposed to high lateral force. Hence these mounting points are kept robust. Different diameters of removable pulleys are located in those mounting points. Here you have to note one thing that, the diameter of the pulley changes with change in bend radius.
Depending upon the cross-section of the material, the peripheral cross-sectional area of the supporting pulleys is kept the same. Depending upon the application, the size and shape of pulleys change.
Quick retraction springs are attached at the front end of the jack for fast and easy retraction of the jack. The springs are designed such that they do not add any additional pressure for the vertical movement of the jack.