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A short class with Sarah and her students. The other ways are under More.
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Today, we're going to explore how a double acting steam hammer works. Can anyone tell me what the main components are?
It has two cylinders, right? An upper and a lower one.
Exactly! When we supply air to the lower cylinder, what happens next?
The hammer goes up into the upper cylinder!
Great! And what happens to the air in the upper cylinder?
It's expelled out through the exhaust.
Right! So this process repeats for the downward stroke as well. Can anyone recap this mechanism?
We push the hammer up with air in the lower cylinder and then push it down with air in the upper cylinder!
Perfect! Remember, we can use the acronym 'UP-DOWN' to recall this process: air in the 'UP' lower cylinder, and air in the 'DOWN' upper cylinder.
Now, let's talk about energy. Do you know where most of the energy for the double acting steam hammer comes from?
Is it from the weight of the hammer?
Good thought, but most energy comes from compressed air or steam, about 90%!
So, lighter hammers can be used because they don’t rely on weight?
Exactly! Lighter hammers are not only efficient but also designed for specific soil types. What's an example of where they shouldn’t be used?
Concrete piles!
Very good! Remember, if you're using high blow rates, you need to be cautious with concrete to prevent damage.
Now, let's find out how diesel hammers operate. What’s unique about the diesel hammer setup?
It's self-contained, so it doesn’t need separate equipment.
Excellent! How does the process start?
You lift the ram and then let it fall.
Correct! As it falls, what happens with the fuel injection?
The fuel pump sprays fuel into the combustion chamber!
Exactly! And what’s the benefit of this explosive energy?
It drives the pile and lifts the hammer back up for the next stroke!
Right! This energy use allows for efficient operation, especially in cohesive soils.
Let's discuss soil conditions. Which hammer type is suitable for normal soils?
The double acting steam hammer!
Correct! And what about the diesel hammer?
It works better in cohesive soil.
Exactly! Cohesive soils provide better resistance, resulting in a better stroke. What happens with too much resistance?
The cycle can stop if the soil is too tough.
Great connection! Always remember the relationship between hammer type and soil resistance when planning your projects.
Steam hammer, steam flow, lift it up, watch it go!
Imagine a tall steam hammer in a construction site, lifting and dropping with the help of powerful steam, creating energy like a giant's heartbeat on the ground.
Remember 'CIRCLE' for hammer types: C for Concrete, I for Impact, R for Rebound, C for Construction, L for Light weight, E for Energy.
HARD for hammer types: H for Heavy, A for Air, R for Resistance, D for Diesel.
Term
Double Acting Hammer
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Term
Diesel Hammer
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Term
Cohesive Soil
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A type of hammer that operates by utilizing air or steam to alternately raise and lower a striking ram.
The frequency at which strikes are delivered by the hammer, typically measured in blows per minute.
Soil that has the ability to stick together, making it denser and often contributing to sticking and higher friction.
A process where fuel ignites from the rising pressure in a combustion chamber.
A technique where the frequency of pile driving is matched with the natural frequency of the pile for optimal operation.
This section discusses the operation and mechanisms of double acting steam hammers and diesel hammers, highlighting their roles in energy generation and pile driving.
The activation and energy generation of double acting steam hammers and diesel hammers are explained in detail. Key points include the upward and downward strokes of the steam hammer, energy derivation from steam, suitable soil conditions for various hammers, and the operational advantages of diesel hammers compared to steam hammers.
In this section, we delve into the mechanisms behind double acting steam hammers and diesel hammers, essential devices for driving piles into the ground.
Mechanism Overview: The double acting steam hammer consists of two cylinders—an upper and a lower cylinder. For the hammer's upward stroke, air is introduced into the lower cylinder which raises the hammer and expels air from the upper cylinder through an exhaust. Conversely, during the downward stroke, air enters the upper cylinder, pushing the hammer down while expelling air from the lower cylinder.
Energy Source: Both upward and downward strokes derive 90% of their blow energy from compressed air or steam, allowing for lighter hammers to be used instead of relying solely on weight. These hammers are suitable for light to medium weight piles and are not suitable for concrete piles due to their high blow rates (95 to 300 blows per minute), which can damage concrete.
Application Scope: These hammers are designed for soils with normal frictional resistance and should not be used in very tight clay or for heavy piles, as they are optimized for lighter conditions.
Self-Contained Unit: Diesel hammers are compact, integrating all components within a single unit requiring no separate compressors or boilers. This feature enhances mobility on construction sites.
Operational Mechanism: The operation starts by lifting the ram with any mechanism, such as a crane, allowing it to fall. As it descends, it activates a fuel pump that injects fuel into a combustion chamber, where the air-fuel mixture is compressed to induce ignition. This not only drives the pile downward but also allows for a rebound action enabling continuous operation without reintegration by external means.
Soil Adaptability: Diesel hammers perform better in cohesive soils where driving resistance and the resulting rebound of the hammer are enhanced. The key operational advantage lies in the double effective blow energy due to combustion, making them viable for various soil types, including tougher conditions.
Understanding these mechanisms is crucial for selecting the appropriate hammer type for specific soil conditions and project requirements.