A forming press, commonly shortened to press, is a machine tool that changes the shape of a work-piece by the application of pressure.[1] The operator of a forming press is known as a press-tool setter, often shortened to tool-setter.
Presses can be classified according to
Shop Press
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Typically consisting of a simple rectangular frame, often fabricated from C-channel or tubing, containing a bottle jack or hydraulic cylinder to apply pressure via a ram to a work-piece. Often used for general-purpose forming work in the auto mechanic shop, machine shop, garage or basement shops, etc. Typical shop presses are capable of applying between 1 and 30 tons pressure, depending on size and construction. Lighter-duty versions are often called arbor presses.
A shop press is commonly used to press interference fit parts together, such as gears onto shafts or bearings into housings.
Other presses by application
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An example of peculiar press control: servo-press
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A servomechanism press, also known as a servo press or an 'electro-press, is a press driven by an AC servo motor. The torque produced is converted to a linear force via a ball screw. Pressure and position are controlled through a load cell and an encoder. The main advantage of a servo press is its low energy consumption; its only 10-20% of other press machines.
When stamping, it is really about maximizing energy as opposed to how the machine can deliver tonnage. Up until recently, the way to increase tonnage between the die and work-piece on a mechanical press was through bigger machines with bigger motors.[6]
Types of presses
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The press style used is in direct correlation to the end product. Press types are straight-side, BG (back geared), geared, gap, OBI (open back inclinable) and OBS (open back stationary). Hydraulic and mechanical presses are classified by the frame the moving elements are mounted on. The most common are the gap-frame, also known as C-frame, and the straight-side press. A straight-side press has vertical columns on either side of the machine and eliminates angular deflection. A C-frame allows easy access to the die area on three sides and require less floor space. A type of gap-frame, the OBI pivots the frame for easier scrap or part discharge. The OBS timed air blasts, devices or conveyor for scrap or part discharge.[7][8]
Comparison of various machine presses Type of press Type of frame Position of frame Action Method of actuation Type of drive Suspension Ram Bed Open-back Gap Straight-side Arch Piller Solid Tie rod Vertical Horizontal Inclinable Inclined Single Double Triple Crank Front-to-back crank Eccentric Toggle Screw Cam Rack & pinion Piston Over direct Geared, overdrive Under direct Geared, underdrive One-point Two-point Four-point Single Multiple Solid Open Adjustable Bench X X X X X X X X X X X X X X X X X Open-back inclinable X X X X X X X X X X X X X X X X X X Gap-frame X X X X X X X X X X X X X X X X X X X X X X X X Adjustable-bed horn X X X X X X X X X X X X X X X End-wheel X X X X X X X X X X X X Arch-frame X X X X X X X X X X X X Straight-side X X X X X X X X X X X X X X X X X X X X X X X X X X Reducing X X X X X X X X X X X X X X X Knuckle-lever X X X X X X X X X X X X X X X X Toggle-draw X X X X X X X X X X X X X X X X Cam-drawing X X X X X X X X X X X X X X X Two-point single-action X X X X X X X X X X X X X X X High-production X X X X X X X X X X X X X X Dieing machine X X X X X X X X X X Transfer X X X X X X X X X X X X X X X Flat-edge trimming X X X X X X X X Hydraulic X X X X X X X X X X X X X X X X X X Press brake X X X X X X X X X X X XHistory
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Proofing press from 1941, cultural monument at the Karlsruhe Institute of TechnologyHistorically, metal was shaped by hand using a hammer. Later, larger hammers were constructed to press more metal at once, or to press thicker materials. Often a smith would employ a helper or apprentice to swing the hammer while the smith concentrated on positioning the work-piece. Drop hammers and trip hammers utilize a mechanism to lift the hammer, which then falls by gravity onto the work.
In the mid 19th century, manual and rotary-cam hammers began to be replaced in industry by the steam hammer, which was first described in 1784 by James Watt, a British inventor and Mechanical Engineer who also contributed to the earliest steam engines and condensers, but not built until 1840 by British Inventor James Nasmyth. By the late 19th century, steam hammers had increased greatly in size; in 1891 the Bethlehem Iron Company made an enhancement allowing a steam hammer to deliver a 125-ton blow.[9]
Most modern machine presses typically use a combination of electric motors and hydraulics to achieve the necessary pressure. Along with the evolution of presses came the evolution of the dies used within them.[10]
Safety
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Machine presses can be hazardous, so safety measures must always be taken. 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, as are light curtains that keep the machine from working if the operator is in range of the die.
References
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Also known as a forming press, a machine press is a tool used in the manufacturing industry to deform a workpiece under high pressure. There are different types of machines presses, including press brakes, punch presses, shop presses and more. The defining characteristic of all machine presses, however, is that they press a workpiece using high pressure to change the shape of a workpiece.
Prior to the invention of the machine press, workers were required to manually hammer metal by hand to change its shape. Not only was this physically taxing, but it was also ineffective when performed on hard and strong metals. Around the mid-1800s, however, the steam hammer hammer was developed. Also known as a drop hammer, the steam hammer was essentially an early version of the modern-day machine press. The only difference is that the steam hammer was powered by steam, whereas most modern-day machine presses are powered by hydraulics.
While the exact mechanics vary depending on the type of machine press, most machine presses work by pressing a plate or die onto or against a workpiece. They are controlled by one or more workers known as “tool setters” who position the workpiece and control the machine press. Once the workpiece is positioned underneath the machine press’s plate or die, the tool setter activates the machine press. Using hydraulic pressure, the machine press pushes the plate or die against the surface of the workpiece, which causes the workpiece’s shape to deform.
Machine presses rely on high pressure to perform their intended applications. With the exception of lighter machine presses, such as arbor presses, most machine presses use around 1 to 30 tons of pressure. As a result, they are able to deform most materials, including bronze, copper, aluminum, iron, steel and composites. The high pressure of a machine presses squishes even the hardest metals, allowing manufacturing companies to deform metal workpieces into their desired shape.
A punch press looks like an ordinary machine press, but it’s used to create holes in workpieces rather than to change the shape of workpieces. Typically controlled via CNC, a punch press holds a die that’s forced against a workpiece using the same high pressure as created by traditional machine presses. The presence of the die allows the punch press to create holes in workpieces.
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