Diesel hammers: types, characteristics and device

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

A diesel hammer is a device that is used to drive piles into the ground. Such devices are divided into several types depending on their parameters. They can differ not only in the type of working tool, but also in weight, which is a rather important factor.

Basic types

To begin with, it is worth noting that the classification of diesel hammers is carried out according to their design features. There are two main types - this is a tubular and rod hammer. As for the tubular type, a fixed pipe is used here. Rod equipment uses two vertical rods as a working tool. In addition, diesel hammers can be divided into several classes depending on the weight of their shock. Today there are three main groups:

• up to 600 kg are light hammers;
• from 600 to 1800 kg - medium weight hammers;
• All tools over 2.5 tons are considered heavy.

The design of these units should be considered separately for each type.

Features of rod type

The design of a rod diesel hammer includes the following main elements:

• piston block mounted on pivot support;
• followed by two vertical guide rods, which are the impact part;
• of course, there is a fuel mixture supply system;
• "cat" is used to fix the structure in the right place.

If we look at the details in more detail, then the piston block is a monolithic structure that is cast inside the hammer body. This block includes not only the piston itself, but also compression rings, hoses for supplying fuel, nozzles for spraying this mixture and a pump that drives the nozzle.

At the rod pile driving diesel hammer, the piston block is located on a hinged support in a stationary state. Two vertical guide rods emerge from the bottom wall of this support. To increase the rigidity of the structure, in the upper part, two rods are interconnected by a traverse. The impact part of the diesel hammer moves along these guide rods during its operation. You can also add that in the lower part of the body of the shock part, there is a chamber for burning the fuel liquid.

Features of tubular type

Tubular diesel hammer differs primarily in that its design is completely unified. The production of this type of unit is carried out according to a long-established pattern. For this reason, any hammer of this type is nothingwill not differ from other tubular apparatus. As for its main elements, they are as follows:

• The main fixation equipment is the "cat". This device has an automatic mechanism that locks and resets as needed.
• It also consists of a striker. This element is presented in the form of a piston, which is equipped with compression rings.
• The next element of the diesel piling hammer is the shabota. This element is the impact surface, which, during operation, comes into contact with an element such as a striker.
• There is also a working cylinder inside which fuel detonation occurs during hammer operation.
• Equipment lubrication and cooling systems are provided.
• Guide tube made of high strength steel.

The main difference between these two types is that the tubular type has a forced water cooling system. This makes it possible to operate the hammer without stopping. While the rod type does not have such a system. Every hour of work should be followed by a break so that the structural elements cool naturally.

Characteristics of units

If we consider the devices of the diesel hammer, the tubular type is considered more efficient, and also has a more advanced design. If we take a hammer of the same weight of a tubular and rod type and compare their effectiveness, we can see that with the same mass, a tubularthe design allows you to drive heavier piles. The difference in weight can be up to two or three times the increase. The main structural parts of these machines are:

• cylinder or rods;
• shock part, striker or woman that moves inside the cylinder;
• shabot, which is the lower part of the hammer, to which the cap is attached.

Operating the device

There are spherical recesses on the woman and the chabot, which, when in contact, will form a fuel combustion chamber. Diesel fuel is injected into this chamber. When the woman hits the chabot, a sufficiently high pressure is created in this chamber, due to which the fuel liquid spontaneously ignites and throws the woman to its highest point. After that, she falls back down again. Thus, pile driving is carried out.

If we compare tubular and rod hammers, we can say with confidence that the second type loses significantly in terms of service life. The tubular design can last about twice as long. Short service life is the main disadvantage of the rod type.

Scope of hammers

The use of a diesel hammer with rods is possible only if the soil has a sufficiently low density index. This is due to the fact that the impact energy of this type of hammers is limited - approximately 27-30% of the potential. The most common type of this type of construction are thoseunits, the weight of the impact striker of which reaches 2500 and 3000 kg. The impact force of such devices reaches 43 kJ. With such indicators, diesel installations are capable of making up to 50-55 strokes in one minute.

As for the use of tubular hammers, they can be used to drive reinforced concrete piles into any type of soil. It is possible to work even on permafrost soil. In this case, the pile is driven into a pre-drilled channel.

The temperature range in which such a unit can operate is from -45 to +45 degrees. However, if the ambient temperature is less than 25 degrees, then the piston block must be warmed up before starting the entire unit.

Depending on the weight, the impact force of the hammer starts from 40 kJ and can reach 165 kJ. The maximum speed of this type of setting is limited to 42 beats per minute.

Tubular Piling Technology

The sequence of work performed by this type of unit is as follows:

• the first stage is the docking of the piston part with the cat, after which they rise to the top position with the help of a copra winch;
• after that, this part and the cat are automatically undocked, as a result of which the impact part falls along the guide;
• while the process of falling occurs, the pump is switched on, which begins to gradually pump diesel fuel into a special recess located in the upper part of the chabot body;
• during the lowering of the piston, the process of compressing the air inside the hammer tube also occurs;
• when the piston hits the chabot, fuel detonation occurs, in which part of the energy is spent on the reverse lifting of the hammer, and the other is used to drive the pile into the ground.

In other words, the immersion and operation of the diesel hammer is due to the impact energy and gas-dynamic energy that occurs during the detonation of the fuel.

Working rod-type hammer

As in the previous case, the work of driving a pile with a hammer of this type takes place in several stages. By the way, the price of a diesel hammer of this type starts from 80 thousand rubles and can reach 1 million rubles or more.

1. To begin with, the process of slinging and fixing the pile in the right place takes place. After that, the "cat" is fixed on the winch of the pile driver. Then it goes down and engages with the impact part of the structure.
2. The next step is to raise the cat and striker to their highest position.
3. When lifting is completed, the operator activates the reset lever. At this moment, the shock part is released and under its own weight falls down towards the hinged head, which is fixed on the pile column.
4. When the head is lowered, the air inside the cylinder is compressed and heated to a temperature of 650 degrees.
5. The moment the hammer hits the articulated head, the pump pumps diesel fuel into the compressed air chamber.
6. During the impact, self-ignition of the fuel occurs. The gas that is released at the moment of detonation throws off the impactorback up.
7. Of course, during the ascent, the speed will decrease rapidly due to the weight of the striker. When the energy runs out completely, the part will rush down again. This circular process will continue until the operator stops the diesel pump.

Pros and cons of design

Despite some differences between tubular and rod devices, they have common positive and negative qualities. Benefits include:

• mobility;
• quite simple and very reliable design;
• energy autonomy;
• The productivity of the machines is quite high.

If we talk about the shortcomings, then there are only three of them. The first is the vibration of the ground, which occurs when struck with a hammer. During operation, a large amount of dust is created, which makes it difficult to work. In addition, the detonation of diesel fuel releases a certain amount of harmful substances into the atmosphere, which pollutes it. The price of a tubular diesel hammer starts from a higher amount - from 320 thousand rubles.