Design and Fabrication Of A Blanking Tool Report – Mechanical projects
Press tools are tools, used to produce a particular component in large quantity, out of sheet metals by using presses.
The different types of press tool operations are blanking, piercing, forming, drawing, cutting off, parting off, embossing, coining, extrusion, perforating, trimming, notching, shaving, lancing, dinking, broaching, curling, bulging, swaging, flaring, etc. Blanking is a process of producing flat components. The entire periphery is cut. The cut-out piece is called blank. This process is called blanking and tool used is called as blanking tool.
For producing any sheet metal components, blanking operation is the primary process to carry-out. In this project, a real time design of a blanking tool and fabrication of a prototype working model is presented.
The press is a metal forming machine tool, designed to shape or cut metal by applying mechanical force or pressure with help of press tool. The metal is formed to desired shape without removal of chips.
Press tools are exclusively intended for mass production work. Sheet metal operation plays an important role in engineering works. Press tool are made to produce a particular component in very large numbers, mainly out of sheet metal. The principle press tool operations are cutting and forming operations of sheet metal.
Sheet metal components such as automobile parts, parts of house hold appliances and electronic equipments are produced by press tools.
Nowadays lot of sheet metals parts are being utilised in lot of sectors irrespective of particular fields like mechanical, electrical, electronics, computers.
Sheet metal components are mainly used for the followings,
- Lesser in weight
- Less Expensive
- Replaceable and better aesthetics
2.5.1 Mechanical Press
The ram is actuated using a flywheel. Stroke motion is not uniform.
1. High forces at bottom of stroke
2. Suited to blanking and punching
2.5.2 Hydraulic Press
Longer strokes than mechanical presses, and develop full force throughout the stroke.
Stroke motion is of uniform speed, especially adapted to deep drawing operations.
1. Longer ram stroke than mechanical types
2. Suited to deep drawing
3. Slower than mechanical drives
CHILD PARTS AND FUNCTION
The blanking tool consists of following major parts and their functions are stated below.
The punch assembly consisting of punch, punch holder and thrust plate is mounted on the top plate with screws and dowels. Shank also screwed to top plate.
Bottom plate is the base of the tool. The die and guide pillars are fitted to this plate. It provides cushioning effect to the die. It employs an opening at bottom to collect the output blanked part.
Blanking Die Plate
Die is one of important cutting tool in the blanking tool. The size or contour of the die opening will be same as the dimension of the desired output component.
Punch is the other important cutting tool in the blanking tool. A force is exerted on the punch by the press to punch the strip placed on the die. The size of the punch will be smaller than the dimension of the desired component. It will penetrate into die for minimum of 3 to 5mm.
After blanking operation when punch is withdrawn back, the blanked part adhere (Stick on) to punch surface. To facilitate removal of part from punch, stripper used. Also it used for guiding punch and to hold the strip flat during punching operation.
While punching the strip, the punch exerts an upward thrust. To prevent that thrust being transmitted to top plate, a thrust or back plate is provided behind the punch. Otherwise it will damage the top plate.
It is a plate used to hold the punch in position without any transition. Punch holder provides a rigid support to the punch during punching.
Guide Bush and Pillar
Guide pillar and bushes are used to align the top and bottom plate. They keep the complete alignment of tool during entire operation.
Shank is a connector between tool and the press ram. It is screwed to the top plate firmly. The individual part drawings with dimensions are followed. All dimensions are in “mm”
Thus a prototype blanking tool is fabricated and its functions have been demonstrated and explained.
The tool could be utilised in mass production to produce identical parts with good geometrical tolerances. By choosing appropriate tool steels for die, punch and other parts, the tool life could increased for maximum range. It has the capacity to blank the sheet up to the thickness of 0.5 mm of mild steel, aluminium and zinc, etc.
Our tool could be used in presses for medium production quantity of 8,000 to 12,000 units. By using the high grade die sets quantity can be increased over 25,000 units.
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