Shearing Operation FundamentalShearing :
A shear force is applied that will cut off part of a sheet. The cut off ‘blank’ becomes the workpiece.
Shearing, also known as die cutting, is a process which cuts stock without the formation of chips or the use of burning or melting. In strict technical terms, the process of "shearing" involves the use of straight cutting bladesorm of sheet metal or plates, however rods can also be sheared. Shearing-type operations include: blanking, piercing, roll slitting, and trimming.
When you apply a high pressure tool through a metal plate and remove part of the metal, the process is called shearing. Shear machining devices include punching machines, which make small discs, and blanking machines, which produce washers and similar objects.
Direct tool ordinary machining is NOT the same as shear machining. With standard tool machining, a single or multiple point tool can be employed to take out a piece of metal from the metal sheet and/or block. This process required repeated pounding of the metal until the required dimensions are achieved. With shear machining, the tool's cutting edge removes the metal from the plate. While this happens, maximum pressure is applied. The tool, however, only touches the metal one time.
Both mechanical and hydraulic machines can perform shear machining. Hydraulic shears cut and score sheet metal quickly and accurately. They work well for factories that do a lot of metal fabrication. In addition, hydraulic shears are best if the operation requires intense pressure. They don't require a lot of maintenance, will operate continuously, and are fast and quiet. Hydraulic shear machines also take up less space than mechanical shear machines while applying the same amount of pressure.
Working Of Hydraulic Shearing Machine:
|Working of Hydraulic Shearing Machine:|
When the metal is inserted into hydraulic machines, it is secured by clamps so it does not shift under high pressure. To ensure that the cut is smooth and even for a 90 degree cut, a squaring arm or back gauge must be used. Minute burrs may be formed by the edge of the cut metal; these must be removed by grinding. If you use hydraulic shears, be careful of the little marks left by the cutting blades and holding clamps while working. You will need to remove them or otherwise account for them
Principle Of Shearing:
To find the shear force for a cut we can go back to the basic mechanics of materials (with one adjustment factor).
F = 0.7twUTS
F = force needed to shear
t = thickness of sheet
w = width of sheet
UTS = Ultimate Shear Strength of material