Power Presses

Group Members:Syed Taha Ahmed (IM-096)Syed Ziauddin (IM-103)Muhammad Hassam (IM-114)Faisal Siddique Awan (IM-118)

IntroductionPresses: The press represents a specific type of machine tool,

essential in the performance of industrial manufacturing processes

Press machines are also the primary machine tool used in metal extrusion and sheet metal fabrication processes.

Presses deliver energy through a force that acts over a distance or stroke

Classifications:Presses can be classified according to their

MECHANISM: Hydraulic, Mechanical, Pneumatic.

FUNCTION: Forging presses, Stamping presses, Press brakes, Punch press.

STRUCTURE: Knuckle-joint press, Screw press.

CONTROLLABILITY: Conventional, Servo-presses.

Classification on the basis of Mechanism

Manual Presses: Either hand or foot operated through levers, screws or gears.

Mechanical presses: These presses utilize flywheel energy which is transferred to the work piece by gears, cranks, eccentrics, or levers.

Hydraulic Presses: These presses provide working force through the application of fluid pressure on a piston by means of pumps, valves, intensifiers, and accumulators.

Pneumatic Presses: These presses utilize air cylinders to exert the required force.

Classification on the basis of Structure Gap Frame Presses: These presses have a

C-shaped frame. These are most versatile and common in use.

Straight Side Presses: These presses are stronger since the heavy loads can be taken in a vertical direction by the massive side frame and there is little tendency for the punch and die alignment to be affected by the strain

Fly Wheel: The flywheel is mounted at the edge of the driving shaft and is connected to it through a clutch.

Clutch: The clutch is used for connecting and disconnecting the driving shaft with the flywheel when it is necessary to start or stop the movement of the ram.

Brakes: The brakes are used to stop the movement of the driving shaft immediately after it is disconnected from the fly wheel

Driving mechanism: The rotary movement of the motor is converted into the reciprocating movement of the ram by crank and connecting rod, eccentric and

connecting rod in mechanical presses Ram: Ram reciprocates to and fro within its guide ways with prescribed stroke

length and power. Ram at its bottom end carries punch to process the work piece. Pitman: It is the part which connects the ram and crankshaft or ram eccentric.

Construction of Gap Frame Press:

Construction of Gap Frame Press:1. Fastest acting Hydraulic Overload Protection

(HOLP), adjustable from 60-100% of rated press tonnage

2. Adjusting screw threads never exposed3. Oil lube to pinion shaft and rear crank

bearings4. AC variable frequency drive5. Taper fit of main gear to crankshaft6. AIDA wet clutch7. Quill mounted flywheel8. Hardened and ground pinion and ground

main gear9. Electric brake on slide adjusting motor

Press working operationsPress working operations may be grouped into two categories:

Cutting operations Forming operations

Cutting Operations:In cutting operations the work piece is stressed by its ultimate strength. The stresses caused in the metal the applied forces will be shear stresses. The cutting operations include:

1. Blanking: Punching or blanking is a process in which the punch removes a portion of material from the larger piece or a strip of sheet metal. The small removed piece is the useful part and the rest is scrap, the operation is called blanking (as shown in fig a).

2. Piercing: It is a process by which a hole is cut (or torn) in metal. It is different from blanking in a way

that small removed part is scrap and the rest is useful (as shown in fig b).

3. Notching: It is an operation in which a specified small amount of metal is cut from a blank. The purpose of notching is generally to release metal for fitting up.

4. Perforating:Perforating is an operation is which a number of uniformly spaced holes are punched in a sheet of metal. The holes may be of any size or shape. They usually cover the entire sheet of metal.

5. Lancing :Creating a partial cut in the sheet, so that no material is removed. The material is left attached to be bent and form a shape, such as a tab, vent, or louver.

6. Slitting :Cutting straight lines in the sheet. No scrap material is produced.

7. Parting :Separating a part from the remaining sheet, by punching away the material between parts.

Forming operations:In this operation , there is no cutting of the metal but only the contour of the work piece is changed to get the desired product. The forming operations include:

1.Bending Bending is a metal forming process in which a force is applied to a piece of sheet metal, causing it to bend at an angle and form the desired shape.

2. DrawingDeep drawing is a manufacturing process that is used extensively in the forming of sheet metal into cup or box like structures

Safety:Machine presses can be hazardous, so safety measures must always be taken.

1. Bi-manual controls: Controls the use of which requires both hands to be on the buttons to operate are a very good way to prevent accidents.

2. Light sensors: That keep the machine from working if the operator is in range of the die.

Thank You