What are Power Hammers?
Power hammers are mechanized forging hammers that have an electric power source or steam that will lift the hammer in preparation for the strike and accelerate it onto the item being hammered. They are also referred to as “Open Die Power Forging Hammers.”
The original power hammer designs were derived from the trip hammer, or “helve hammer” and have been in use since the late 1880s by blacksmiths, bladesmiths, metal workers, and manufacturing.
Design and operation
Typical power hammers comprise a frame, an anvil, and a reciprocating ram that has either a hammerhead or a die attached. The workpiece is placed on the lower anvil or die, while the ram or upper die impacts the workpiece.
The power hammer is an evolved version of the trip hammer. However, the power hammer uses arranged mechanical linkages and springs, or compressed air, or steam, to store potential energy, and additionally, it is able to accelerate the ram on the downward stroke.
This coupled with the mass of the ram or hammerhead can impart more force than was possible by letting the weight fall alone.
The hammer’s predecessors like trip hammers, steam hammers, drop hammers, board hammers or strap hammers, all allowed the power source to raise the ram or hammerhead but let it go only by gravity.
Power hammers are rated by the weight of the moving parts that directly impact the working piece. On the power hammer, this would include the weight of the moving components which could be an upper die, ram, mechanical linkages arms and spring(s) or a ram, piston and construed connecting rod(s).
Specific design features dictated by the power source. The heaviest power hammer, which was steam-powered, was rated at 125 short tons (113 t).
Types of Power Hammers
There are various different types of forging power hammers that are widely used in the market.
- Pneumatic Hammers
- Steam or Air Hammers
- Helve Hammers
- Hydraulic Power Hammer
- Lever-Spring Hammers
1. Pneumatic Power Hammer
Pneumatic power hammers are another conventional type of machine which carries the cylinder in which the piston operates. This piston is connected to the main motor shaft by a crank and a connecting rod. A hand lever operates the air valve.
Air is supplied through the various cylinders. There an additional piston works in the cylinder which holds the tup, which has a low lift. This piston slides on fixed guides.
In order to raise the tup, the piston in the cylinder is lowered to create a vacuum above the piston in the adjacent cylinder, which causes a suction effect on the piston and thereby lifts tup.
Close to the end of the upward stroke of the in-cylinder piston, air is forced in succession from the air cylinder to the adjacent air cylinder, where the air is compressed when the piston is in the upward stroke.
This motion is responsible in turn for returning the piston and then moving the tup with speed downwards. This action cycle is repeated at intervals depending on the blows are required.
2. Steam or Air Power Hammer
A steam-powered hammer is defined as those that can be worked on by steam or compressed air. They consist of a moving ram, rod, and piston, a lifting tool, a double-acting high-pressure steam cylinder, a housing or frame, and an anvil.
These are forging power hammers in which the steam runs in at first, and then the piston and moving parts (mass approximately 5000kg) are lifted up by steam pressure at a speed of 3m/sec.
When the blow is required, the lever is automatically actuated so that the top sliding valve is opened to receive steam from above the cylinder and allows exhaust steam to exit through the bottom, thus the required blow is produced.
3. Helve Power Hammer
A helve power hammer is also known as a trip or tilt power hammer that is a large powered hammer. These forging power hammers are when there is more than one helve hammer that are fitted into a forge, which is also called a hammer mill.
Most of these forging power hammers are lifted with a cam and then the cam is released to use the force of gravity to drop it. Helve hammers are mechanical devices which are mostly hydraulically driven, by water wheel.
Also, these are used to convert blooms which are made of iron into more usable bar iron in the finery forges.
4. Hydraulic Power Hammer
Hydraulic hammers also called hydraulic presses develop 200 to 300 times oil pressure compared to atmospheric pressure in a hydraulic cylinder.
While hydraulic presses have a ram or press combined with a hydraulic drive, hydraulic hammering has quicker production with hydraulic processes through a simple squeeze operation.
Hydraulic hammering has reduced noise and vibration as speed, low pressure, and die travel are performed automatically with the hydraulic process. Hydraulic presses are not uncommon today that can deliver a force of 75000 tons.
Hydraulic presses are used in forging industries that typically produce from 1000 tons to 10000 tons. Hydraulic presses are primarily used for the production of nuts, bolts, screws, and rivets.
5. Lever Spring Hammer
A lever-spring hammer is a relatively light type of power hammer that is primarily used for small forgings. These types of hammers consist of a hefty frame that has a vertical projection above it, which acts as a housing to a bearing in which the laminated spring is oscillating.
There are two ends to this string: one end supports the connecting rod and the other end supports a vertical tup. The tup holds the weight and moves vertically up and down in the fixed guides.
The connecting rod’s lower end is attached with an eccentric sheave. In addition, the sheave is attached to the crank wheel that is powered by a treadle that moves it down.
Therefore, the sheave moves from the crank wheel, and this causes the laminated spring to oscillate in the bearing.
As the spring oscillates back and forth, this causes the tup to move up and down, which produces the repeated blows needed to strike the job. The hand lever can be operated to adjust the stroke of the connecting rod, and degree of blows.
FAQs
What is a power hammer used for?
Power hammers are particularly effective in the forge welding process by bladesmiths to create knives, blades, and more. They are also commonly used to forge striking steel tools and closing rivets.
What size power hammer do I need?
If you are a production shop and are working 1 to 2″ stock, a 34 will do the job… however a 68 or 106 or larger hammer will do it faster. If you are a hobby shop and your work will not exceed 1 to 2″, then a 33 will do the job.
Are power hammers still made?
Many may still be seen in use in small manufacturing and artist-blacksmith shops today. In the middle of the 20th century power hammers driven by compressed air began to gain popularity and several manufacturers are currently producing these hammers today.
What are the different types of power hammers?
Common types of power hammers in blacksmithing
1. Steam power hammer. Steam hammers are typically the largest and most powerful types of power hammers.
2. Air-lift hammer. Air-lift hammers raise the ram using compressed air and are the most common power hammer found in modern blacksmith shops.
3. Mechanical power hammer. Mechanical power hammers are typically smaller than other types and run on an electric motor.
How old are power hammers?
They are also called open die power forging hammers. They have been used by blacksmiths, bladesmiths, metalworkers, and manufacturers since the late 1880s, having replaced trip hammers.
What is the difference between a power press and a power hammer?
Each machine forges steel in a different manner. A press forges steel from the inside out. A hammer forges steel from the outside in.