The hydraulic press It is a machine made up of pistons, which move in cylinders joined by communicating vessels filled with fluid, which acts to multiply the force. When a small force is applied to the inlet piston, the system offers a greater force to the outlet piston.
This greater force is used in the metalworking industry, to compress and cut metals, giving them the form of pieces or mechanical parts necessary to assemble cars, airplanes, electrical appliances and more..
It can also be used to lift heavy weights, exert traction, extract oil from seeds, and straighten deformed metal parts..
As they are almost always low maintenance and safe to use, hydraulic presses are a must in the industry. That is why they are manufactured in countless models and sizes, including smaller presses for domestic use..
Its operating principle is very simple, it is based on the so-called Pascal's law. This states that the pressure applied to a fluid confined in a container is fully transmitted to each part of the fluid and the walls of the container. It is then that through the fluid, the applied force is transmitted and multiplied at the output.
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Presses based on various mechanisms have been used since ancient times, to compress, laminate, cut and many more functions.
But the first hydraulic press, based on Pascal's principle, is due to Joseph Bramah, an ingenious mechanic who was born in 1749 in the town of Stainborough, England. That is why the hydraulic press is also known as Bramah press.
At first the Bramah press did not produce great forces. For this reason it was not suitable for minting coins or working metals on a large scale. But shortly after, in 1797, the brothers Jacques and Auguste Perier improved the design by reaching pressures greater than 70 kg / cmtwo.
A new optimization appeared in the mid-19th century, thanks to a Scottish machinist named John Haswell, who worked for the Austrian railways..
Since then, the hydraulic press became part of the tools in heavy industry to the present day, with much improved designs involving computerized control systems..
This principle was discovered long before Bramah, in the 17th century, by the French scientist Blaise Pascal (1623 - 1662)..
Pascal was a very prolific inventor during his short life. He became interested in mathematics, made important contributions to probability theory, and invented a mechanical calculator, called the pascaline.
Previously, the experiments on vacuum and pressure had come to Pascal's hands, made by Evangelista Torricelli, assistant to the now elderly Galileo Galilei.
After much observation, he put his principle into practice by bursting a barrel full of water, adding just an additional 1 kg of water through a high-rise pipe..
Pascal managed to break the barrel thanks to the fact that water is not a very compressible liquid, that is, it does not change its volume easily. So if the water is confined and a small force is applied through a small piston, the pressure created, which is force divided by area, is large..
The force is thus transmitted to each molecule of the fluid and to the walls of the container equally.
If the container is tightly closed like the barrel, enough pressure will pop it. But if instead there is a moving piston at the other end, the force displaces it and can push or raise an object that is placed on top. This is how the hydraulic jack works.
In the following diagram you can see Pascal's principle: a smaller force F1 applies to small piston of area S1, thanks to which it produces a force Ftwo greater, since it depends on the quotient (Stwo/ S1), which is greater than 1. Since the pressure is the same everywhere:
p = F1 / S1 = Ftwo / Stwo
From which it follows that the magnitude of the force transmitted to the largest piston is:
Ftwo = (Stwo / S1). F1
As previously indicated, the hydraulic press has a variety of functions:
-Compress and pull.
-Cut parts for a multitude of equipment.
-Rolling the metal.
-Squeeze fruits and seeds for oil extraction.
-Extract parts.
-Straighten deformed steel parts.
The hydraulic press works by applying a small input force, which will be amplified by the fluid to obtain a certain output force. This is achieved with the basic device described, in addition to several complementary systems.
The fluids used are diverse, usually derived from hydrocarbons and some presses contain more than one.
A modern hydraulic press is basically composed of:
-Hydraulic system, based on the described Pascal principle, which contains the hydraulic fluid, pistons, valves, filters, hoses and pipes, which complement the system. There are also pressure gauges to check the pressure and with it the output force.
Now, there are manual hydraulic presses such as hydraulic jacks for vehicles, but the most common in laboratories and industries is that they have a motor. Therefore several additional systems are also required:
-Electric system, consisting of a starting system, wiring, coils, connectors and fuses.
-Power system, with a motor and a pump.
-Computerized control system, contains the electronics necessary to operate the press according to job requirements.
The properties of materials used in construction and manufacturing are tested through controlled trials.
With the help of the press, the samples are compressed or stretched little by little and the deformations they undergo are recorded. In this way it is known how much they resist before permanently deforming and breaking.
A tool called die, which among other functions, allows cutting the metal sheets according to the design templates.
In this way, the metal parts that make up the car body and other vehicles are cut..
In addition to being used to create body parts, the hydraulic press has other uses in the automotive industry, such as the assembly of various parts. That is why it is very useful in the mechanical workshop.
A large amount of metal is found in end-of-life items, which can be reused, but must first be collected and stored.
Compaction machines reduce the volume of the metal, so it can be stored in smaller spaces while it is being used again. They can also reduce the volume of other waste materials for recycling, such as boxes and cartons..
There are hydraulic presses designed to process fruits and seeds, as well as oil extraction.
The drugs come in many forms. Pills and tablets with the precise size and dosage are manufactured using hydraulic presses that compact the compounds.
Presses are also used in the manufacture of compact powder shaped cosmetics.
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