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.
Main 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 a rod hammer. As for the tubular type, a fixed tube is used here. At the rod equipment, two vertical rods are used as a working tool. In addition, diesel hammers can be divided into several classes depending on the weight of their impact part. Today there are three main groups:
- up to 600 kg are light hammers;
- from 600 to 1800 kg - medium-weighted hammers;
- all instruments weighing more than 2.5 tons are considered heavy.
Consider the design of these units should be separately for each type.
Rod Type Features
The design of a diesel rod hammer includes the following main elements:
- there is a piston block on the hinge support;
- then follow two vertical guide rods, which are the shock part;
- naturally, there is a fuel mixture supply system;
- A “cat” is used to fix the structure in the right place.
If we consider 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 piling diesel hammer, the piston block is located on the hinged support in a stationary state. Two vertical guide rods extend from the bottom wall of this support. To increase the rigidity of the structure, in the upper part two rods are connected by a traverse. The shock part of the diesel hammer during its operation moves along these guide rods. You can also add that in the lower part of the body of the shock part, there is a chamber for burning fuel fluid.
Features of tubular type
The tubular diesel hammer is distinguished primarily by the fact that its design is completely unified. The production of this type of unit is carried out according to a long-established scheme. For this reason, any hammer of this type will not be different from another tubular apparatus. As for its main elements, they are as follows:
- The main fixation equipment is the cat. This device has an automatic mechanism, which is fixed and reset as necessary.
- It also consists of a shock striker. This element is presented in the form of a piston, which is equipped with compression rings.
- The next element of the diesel hammer for driving piles is a Shabot. This element is a shock surface, which in contact with such an element as the firing pin.
- There is also a working cylinder, inside of which the detonation of fuel occurs during the operation of the hammer.
- 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 accompanied by a break so that the structural elements cool naturally.
Unit Specifications
If we consider the device of a diesel hammer, then the tubular type is considered more efficient, and also has a more advanced design. If you take a hammer of the same weight of the tubular and rod type and compare their effectiveness, you can see that with the same weight the tubular structure allows you to hammer heavier piles. The difference in weight can reach two or three times the increase. The main structural parts of these machines are:
- a cylinder or rods;
- shock part, hammer or woman, which move inside the cylinder;
- Shabot, which is the lower part of the hammer to which the headgear is attached.
Device operation
There are spherical recesses on the woman and the Shabot, which upon contact will form a fuel combustion chamber. Diesel fuel is injected into this chamber by injection. When a woman hits a swab in the chamber, a rather high pressure is created in this chamber, due to which the fuel liquid spontaneously ignites and throws the woman to its upper point. After that, she falls back 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 two times longer. Low life is the main drawback of the rod type.
Scopes of hammers
The use of a diesel hammer with booms 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 hammer is limited - approximately 27-30% of the potential. The most common type of this type of construction are those units whose shock hammer weight reaches 2500 and 3000 kg. The impact force of such devices reaches 43 kJ. With such indicators, diesel engines are capable of making up to 50-55 strokes in one minute.
As for the use of tubular hammers, they can be used to immerse reinforced concrete piles in any type of soil. It is possible to work even on permafrost. In this case, the pile is clogged into the pre-drilled channel.
The temperature range in which such a unit can operate is in the range from -45 to +45 degrees. However, if the ambient temperature is less than 25 degrees, then before starting work, heating of the piston block is required before starting the entire installation.
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 installation is limited to 42 beats per minute.
Pile dip technology
The sequence of work 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 upper position with the help of a copra winch;
- after that, in the automatic mode, this part and the cat are undocked, as a result of which the shock part falls along the guide;
- while the process of falling occurs, a pump is turned on, which gradually begins to pump diesel fuel into a special cavity located in the upper part of the cabinet;
- during lowering of the piston, the process of air compression inside the hammer pipe also occurs;
- when the piston strikes against a rampart, fuel detonation occurs, in which, part of the energy is spent on the hammer returning up, and the other on driving the pile into the ground.
In other words, the immersion and operation of the diesel hammer occurs due to the impact of shock energy and gas-dynamic energy that occurs during fuel detonation.
Work 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 at 80 thousand rubles and can reach 1 million rubles or more.
- To begin with, the process of slinging and fixing the pile in the right place is going on. After that, the "cat" is fixed on the winch Koprov. Then it goes down and engages with the shock part of the structure.
- The next stage is raising the cat and the striker to their highest position.
- When the lift is complete, 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 mounted on the pile column.
- When the striker lowers, inside the cylinder the air is compressed and warmed up to a temperature of 650 degrees.
- When the hammer hits the hinged head, the pump pumps diesel into the chamber with compressed air.
- Self-ignition of the fuel occurs during impact. Gas, which is released at the moment of detonation, throws the shock part back up.
- Naturally, during the rise, the speed will decrease rapidly due to the weight of the striker. When the energy has completely dried up, the part will again rush down. This circular process will continue until the operator shuts off the diesel pump.
Pros and cons of design
Despite some differences between tubular and rod devices, they have common positive and negative qualities. The benefits include the following:
- mobility;
- quite simple and very reliable design;
- energy autonomy;
- machine performance is quite high.
If we talk about the shortcomings, then there are only three. The first is the vibration of the soil that 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 emits a certain amount of harmful substances into the atmosphere, which pollutes it. The price of a tubular diesel hammer begins with a higher amount - from 320 thousand rubles.