What is a hydraulic press made of. How does a hydraulic press work?? Where it is used?
How much force can you squeeze in your hands?? You might be a strongman, and you have a lot of strength. But no matter how strong you are, you can’t squeeze oil out of a sunflower seed by hand. You need a press for that.
Having even a small hydraulic press and knowing the physics you can multiply the power of your hands dozens or even hundreds of times.
And then you can squeeze oil, crush plastic bottles and cardboard, and even turn a huge pile of tin cans into a small pile of tin tortillas with no problem.
What is the principle of the hydraulic press that it allows you to multiply the applied force many times literally out of nothing?
The principle of the hydraulic press
A hydraulic press is a machine for pressurizing materials, driven by a squeezing liquid. It is based on Pascal’s law, who incidentally invented the hydraulic press, but he called it a “machine for increasing forces”.
A hydraulic press is made up of two differently sized containers connected to each other and filled with mineral oil or water. Since the pressure in liquids is transferred equally in all directions, applying a certain pressure to the liquid in the small vessel, we obtain the same pressure in the large vessel per unit area.
But since the cross-section of a large vessel will be much larger, the pressure exerted over the entire area of the section will be as many times greater as the area of this section.
And by placing between the liquid column in the larger vessel and the stationary support, we obtain a pressure on the body that is several times greater than the applied pressure.
For example, if we have a hundredfold difference in the cross-sections of the vessel, then the resulting force will be a hundredfold greater than the applied force. That’s how you can increase the power of your hands many times without using additional sources of force.
Hydraulic press with their own hands
Industry produces various versions of presses for different purposes. The production of cardboard, plywood is unthinkable without it. In metallurgy, the use of presses has become an integral part of almost all metalworking processes.
Hydraulic devices, based on the same principle, are nowadays perfectly familiar parts of cars, bicycles and so on.
However, the hydraulic press can also be made by your own hands. Experience shows that often homemade hydraulic presses are not only as good as their factory counterparts, but are even superior to them.
This requires some tools, properly attached hands and, of course, “brains”. Blueprints and recommendations, how to make a hydraulic press at home on the Internet abound, the main thing. is to follow the rules of safety.
And making the press will cost you several times less than buying the factory version.
Manual hydraulic press. The Great Encyclopedia of Oil and Gas, article, page 1
Manual hydraulic press
Manual hydraulic press ( Fig. 50) consists of a steel cylinder with a piston in which a punch is inserted, a pump, an oil reservoir that is also the press handle, a manual pump drive to pump oil from the oil reservoir into the press cylinder, and a fork. The fork has a matrix, which is fixed by a bar with a screw. [2]
Manual hydraulic press RGP-7m ( Fig. 31, b) consists of a body 12, a pump 13 with valves, a piston 18 with a punch, an oil reservoir 15, a fork 17 with a matrix and a pump lever 14. When the pump lever is swung by the oil pressure, the piston with the pu-axon moves and the pressure is pressed. [4]
Manual hydraulic press PGR-20M weighing 5 3 kg is designed for termination, connection of aluminum and copper insulated wires and cables with conductors cross section 16. 240 mm2 press by multi-sided crimping, and manual mechanical press RMP-7M 7 kg. for pressing cable lugs on wires and cables with copper and aluminum conductors cross section 16. 240 mm2 one-tooth and two-tooth crimping. [5]
Manual hydraulic press PGR-20M1 (fig. 17) consists of the body 2, which is the working cylinder, bracket / mounted on a thread on the body which houses the matrix and punches, stop valve, handle 6, cup 3, which connects the body to the handle, the lever 4, mounted pivot on the cup, an oil cylinder. Working liquid for the press is oil AK-Yu. [6]
Manual hydraulic press RGR-7M is intended for connection and termination of copper and aluminum conductors and cables with cross section 16. 240 mm2 by method of pressing in tubular cable lugs and connecting sleeves, by single-jaw local indentation, and also for aluminum conductors with cross section from 16 to 95 mm2 by double-jaw indentation. [7]
Manual hydraulic press of RGP-7m type with a developing maximum force of 7 ton-force is produced by Noginsk experimental factory of mounting devices of the USSR Ministry of mounting and special construction. It is universal mechanized tool. [8]
Manual hydraulic press PGR-20 (fig. 2.4, b) working fluid is AK-YU oil. [10]
RGP-7m manual hydraulic press is designed for crimping of cable lugs on conductor cores and cables with cross-section from 16 to 240 mm 2 with single-jaw indentation, and from 16 to 95 mm 2 with double-jaw indentation. [12]
The pressure of the gate valve is raised by means of a manual hydraulic press up to 25 ati. When the pressure is steady, the time is recorded, and after 5 minutes. If the pressure were to drop, during that 5 min. [14]
The principle of the hydraulic press is based on the law of communicating vessels. For example, there are two connected vessels of different sizes. Once the liquid is poured in, it’s evenly distributed. If the quiescent state is broken and the pressure in the smaller vessel is increased, then in the larger vessel the applied force will increase in proportion to the size difference. The device obeys the rule: the gain in force is equal to the loss in distance.
Blaise Pascal invented the work of a hydraulic press, but he called it a “machine for increasing force. Previously, the benefit of such a machine seemed minuscule, but now engineers were using Pascal’s insights in making it easier to work.
The diagram shows a simple hydraulic press consisting of large-diameter and small-diameter pistons set in communicating cylinders, with fluid underneath the pistons. The force F1 is exerted on the small-diameter piston with area S 1, let us determine the force F2 that can be overcome by the piston with area S2.
The pressure under piston 1 can be calculated by the formula: p1=F1/S1
Pressure under piston 2 will be determined by the relationship: p2=F2/S2
According to Pascal’s law, the pressure applied to a fluid is transferred to all points of that fluid equally in all directions.
Types of hydraulic presses
According to the All-Russian Classifier of Fixed Assets, the hydraulic press belongs to the group Including all metal-working press-forging machines and hammers.
Classification by type of cylinder arrangement:
- With closed frame. the frame has holes to fix the press on the table; used for bending, straightening, unpressing/pressing.
- With open frame. for processing parts of irregular shape and inconvenient design; performs similar operations.
- Universal. they have a complete set of functions; the hydraulic pump can be used manually.
- Press brakes. used for mounting/dismounting, pressing/unpressing. Small dimensions allow its use under any conditions of use.
Modern presses cannot do without CNC control. Once the operating mode and pressure have been selected, there is no need to constantly monitor the machine. the microcomputer does the job.
Classification
Generally speaking, hydraulic presses are subdivided into vertical presses (for stamping, pressing, etc.) and horizontal presses (for drawing, forming, etc.).д.) and horizontal presses (for bending, cutting, straightening, etc.).п.), however, there are major design differences in the structure and number of pumps used. Thus, low-pressure and high-pressure pumps are often used together: the former. for guided movements of the press bodies, the low-pressure pumps are used for the high-pressure operation in resource-intensive pressing operations. for generating high pressures in resource-intensive pressing operations. Readers who are seriously interested in the design features of the various types of hydraulic presses, we recommend to refer to the relevant specialized literature freely available on the Internet.
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Hydraulic press: types, applications
Hydraulic press is a device designed to create high pressure in the processing of metals and other materials. It consists of two cylindrical vessels equipped with pistons of different diameters. The operating principle of the hydraulic press is based on the law of hydrostatics, which states that the fluid in the vessels transmits the same pressure in all directions. A special oil is most often used to obtain the hydraulic press force, it ensures the transmission and increase of the pressure force to the required value.
- stamping of parts made of steel, aluminum, plastic and other materials;
- pressing of metal parts;
- Pressing of carbon blocks and wood chips;
- hot and cold metal punching and cutting, straightening of defects.
Hydraulic presses are widely used in car repair shops and service stations for such works:
- production of bearings and bushings;
- punching of various parts;
- pressing of spare parts;
- repairing defects in metal body parts;
- metal bending.
You can find specialized and universal presses on sale. Universal units are designed to perform a wide range of works: straightening and bending parts, assembly and disassembly of units with pressing and pressing. The simplest press is used for pressurizing sleeves and lugs. In car repair shops that specialize in tire repair, vulcanizing presses are used.
Types of hydraulic presses for service stations
Before buying a device it is necessary to evaluate the following parameters:
- power (the maximum force exerted by the rod to the material);
- length of the rod;
- installation method;
- the presence of a pressure gauge;
- type of pressure actuator;
- the type of safety system responsible for blocking the machine’s operation in case of failure;
- The presence of an automatic cylinder return system, which will reduce the physical effort of the craftsman;
- the weight of the device.
The more options the press has, the better. Preferably, the frame construction of the unit should be of solid steel or steel profile.
Communicating vessels
Communicating vessels are those in which fluid can flow freely from one vessel to another. The shape of the communicating vessels can be different. In communicating vessels, a liquid of the same density is set at the same level if the pressures over the free surfaces of the liquid are the same.
From Fig.1 we see that structurally a hydraulic machine. are two communicating vessels of different radius. The heights of the fluid columns in the cylinders will be the same if no forces act on the pistons.
Pascal’s law
Pascal’s law tells us that the pressure exerted on a fluid by external forces is transmitted to it without change to all its points. Pascal’s law is the basis for many hydraulic devices: presses, braking systems, hydraulic drives, hydraulic boosters, etc.д.
One of the simplest and oldest devices based on Pascal’s law is a hydraulic press in which a small force F_1, applied to a piston of small area S_1, is converted into a large force F_2, which acts on an area of large area S_2.
The pressure that the number one piston creates is equal:
The pressure of the second piston on the fluid is:
If the pistons are in equilibrium, the pressures p_1 and p_2 are equal, hence, we can equate the right parts of expressions (1) and (2):
Determine what will be the modulus of force applied to the first piston:
From formula (4), we see that the value of F_1 is \frac times the modulus of force F_2.
And so, using a hydraulic press, it is possible to balance a much larger force with a small force. The ratio of \frac shows the gain in force.
The press works like this. The body to be pressed is placed on a platform which rests on the large piston. Use the small piston to create a high pressure on the fluid. The large piston together with the body to be compressed rises, rests against the fixed platform above them, the body is compressed.
The liquid is pumped from the small cylinder to the large cylinder by repeated movement of the small area piston. This is done as follows. The small piston rises, the valve opens and fluid is sucked into the space below the small piston. When the small piston descends, the liquid, exerting pressure on the valve, closes it, while opening the valve, which lets the liquid into the large vessel.
The formula for a hydraulic press
How much force can a hydraulic press produce??
To answer this question, let’s imagine a hydraulic press with two cylinders. A force F_ is exerted on a small piston of area S_. It creates some pressure p_.
The pressure in the large piston p_ acts on the large piston of area S_, and creates a force F_.
The pressure is equal to the ratio of the force to the area of its application:
Since the cylinders are communicating, the pressure in both cylinders is equal according to Pascal’s law:
Substituting the expressions for pressure into both parts of this formula, we get:
The force exerted by the large piston is as many times the force exerted on the small piston as the area of the large piston is as large as the area of the small piston.
Hydraulic press as lever
It would seem at first glance that a hydraulic press can produce force out of nowhere and do more work without expending any energy. However, this is not the case.
The amount of work produced is equal to the product of the force by the distance traveled by the force. As long as the pistons are stationary, the work is zero. However, if the pistons start moving, the small piston travels as much distance as its area is smaller than that of the large piston.
It turns out that the gain in force on the large piston is achieved by losing the distance on the small one. In fact, a hydraulic press is a lever of the first kind, where the small cylinder is the long arm and the large cylinder is the short arm.
Hydraulic press construction: principle of operation, scheme
Modern mechanisms, machines and tools, in spite of their seeming complexity, are a set of so-called simple machines: levers, screws, gates and the like. The principle of operation of even very complex devices is based on fundamental laws of nature, which are studied by the science of physics. Let us take the structure and operating principle of a hydraulic press as an example.
What is a hydraulic press
A hydraulic press is a machine that exerts a force much greater than the force initially exerted. The name “press” is rather arbitrary: such devices are often actually used for compressing or baling. For example, to obtain vegetable oil, the seeds of oil-bearing crops are pressed together vigorously, squeezing the oil out. Hydraulic presses are used in industry to manufacture goods by punching.
But the principle of a hydraulic press can also be used in other applications. The simplest example: a hydraulic jack is a mechanism which allows the application of a relatively small effort by human hands to lift loads whose mass is certainly beyond human capabilities. The same principle. the use of hydraulic energy. is the basis for the operation of various mechanisms:
The popularity of this kind of mechanisms in the most diverse fields of technology is due to the fact that enormous energy can be transmitted through a fairly simple device consisting of thin and flexible hoses. Industrial multi-ton presses, crane jibs and excavators. all of these machines, indispensable in today’s world, work efficiently thanks to hydraulics. In addition to industrial devices of gigantic power, there are many manual mechanisms, such as jacks, clamps and small presses.
How does the hydraulic press work?
To understand how this mechanism works, you need to remember what communicating vessels are. This term in physics refers to vessels connected together and filled with a homogeneous liquid. The law of communicating vessels says that a homogeneous fluid at rest in communicating vessels is at the same level.
If we disturb the quiescent state of a liquid in one of the vessels, for example, by refilling it or by applying pressure to its surface in order to bring the system to the equilibrium state that any system seeks, in the other communicating vessels the liquid level will rise. It is based on another physical law, named after the scientist who formulated it, Pascal’s law. Pascal’s law is as follows: the pressure in a liquid or gas extends to all points equally.
What is the operating principle of any hydraulic mechanism based on?? Why can one easily lift a car weighing more than a ton to change a tire??
Mathematically, Pascal’s law has this form:
Pressure P is directly proportional to the applied force F. This is clear. the more pressure, the greater the pressure. and inversely proportional to the area of the applied force.
Any hydraulic machine is a communicating vessel with pistons. The schematic diagram and design of the hydraulic press are shown in the photo.
Imagine pushing on the piston in the bigger vessel. According to Pascal’s law, pressure began to spread in the liquid of the vessel, and according to the law of communicating vessels, to compensate this pressure, in the small vessel the piston rose. If the piston in the big vessel moves one distance, then in the small vessel this distance will be several times greater.
In carrying out the experiment, or mathematical calculation, it is not difficult to observe the following regularity: the distance at which the pistons move in vessels of different diameter depend on the ratio of the smaller area of the piston to the larger area of the piston. The same thing will happen if, vice versa, a force is applied to the smaller piston.
According to Pascal’s law, if the pressure produced by the action of a force applied to the unit area of the piston of a small cylinder extends equally in all directions, then the large piston will be subjected to the same pressure, only increased by as much as the area of the second piston is larger than that of the smaller.
This is the physics and construction of a hydraulic press: the force gains depend on the ratio of the piston areas. By the way, the hydraulic shock absorber uses the opposite ratio: a large force is dampened by the hydraulic shock absorber.
The video shows a model of the hydraulic press, which clearly illustrates how this mechanism works.
The design and operation of the hydraulic press is subject to the golden rule of mechanics: winning in force, losing in distance.
From theory to practice
Blaise Pascal, having theorized about the principle of the hydraulic press, called it a “machine for increasing forces”. But it took more than a hundred years from the theoretical to the practical realisation. The reason for this lag was not the uselessness of the invention. the benefits of the machine for increasing force are obvious. Numerous attempts have been made by designers to construct this mechanism. The problem was the creation of a seal that would keep the piston close to the vessel wall and at the same time allow it to slide easily, minimizing friction costs. rubber did not exist back then.
The problem was solved only in 1795, when the English inventor Joseph Brama patented a mechanism called the “Brama press”. This device later came to be called a hydraulic press. The operating principle of the device, theorized by Pascal and embodied in Brama’s press, has not changed over the centuries.
The other area of application of the press: hydraulic press for cable lugs
The hydraulic press is commonly used for pressing lugs on high-voltage cables. With the help of the device the process of mechanical compression of the connection is performed, which after processing will have greater strength, conduct electricity well, not to overheat, which reduces the likelihood of damage to the contacts and the emergence of accidents.
Crimping of cable lugs can be done with the help of presses
A manual hydraulic lug press is particularly suitable for cables of 5. 400 mm². Some device parameters should be taken into account when choosing a tool. Presses must have a pressure-limiting valve. These devices are more reliable because they prevent exceeding the allowable pressure.
An important criterion is the type of press head, which can be open or closed. The first option provides more convenient and easy operation at any cable length. To work with a closed type press, you must first open the stopper, take out the matrix, insert the wire and the tip, close the fixture. Only after these manipulations the cable is crimped.
When choosing a hydraulic press it is important to consider the diameter of the working section of the cable. Depending on this, all models of the tool can be divided into types. The PG-70 variant is used for conductors with a cross section of 4-70 mm². Type PG-120 is designed for cable diameters of 10-120 mm², PRG-240. 16-240 mm². PGR-300 hydraulic press is able to work with cables of 16-300 mm² in diameter. Model PG-1000 is designed for cables with a diameter of 400-1000 mm².
All models can work with copper or aluminum wires. Many modern devices are equipped with a quick turn mechanism and rotating heads. KVT manual hydraulic presses of domestic manufacturer are very popular. This is due to democratic cost of the tool and high quality of its performance.
Hydraulic press PG-1000 is used for cables with diameter of 400-1000 mm²
Important! In the kit of the hydraulic press KVT includes eight removable matrixes for pressing.
What can you make a hydraulic baling press
The most popular device for making a hydraulic press is a jack, the actions of which are based on the principle of hydraulic. The laws of physics dictate that the liquid under pressure does not reduce its volume. Therefore there is no loss of power when acting on the workpiece to be machined. In addition the jack is characterized by high efficiency, thanks to which you can count on a significant compression force.
To make a homemade device, you can use the scheme of the hydraulic press from the jack, which can be found on the Internet. The first step is to create the frame of the structure from the steel profiled tube, metal angles and plate. The jack is placed between the retaining plate and the platform, making sure that when it is in retracted position, the tip of the jack is inside the retainer. The base of the tool is bolted to the mobile stop.
For pressing metal workpieces the workpiece is placed on a platform, the jack is lifted by acting on its lever. The process of squeezing. It is important to know how to lower the hydraulic jack, what should be done at the end of the work. For this purpose, the tool is equipped with a bypass valve. It is a round head with protruding shoulders. It must be loosened, causing the device to lower.
The jack also has a shutoff valve, which when closed, pumps oil into the piston. Normal operation of the device indicates that there is sufficient fluid in the system. If the tool is running slowly or has stopped completely, it means there is not enough hydraulic oil in the tool. You need to know how to refill the oil in the hydraulic jack. To do this, there is a special filling plug on the body of the device, which should be unscrewed. Then the reservoir is filled to the desired volume. After the procedure is completed, the jack is pumped.
Hand hydraulic press is a multifunctional equipment, which is widely used in car services. This is an indispensable helper for the home workshop. When choosing a device it is important to determine the scope of its use. For domestic purposes, the device designed for the force up to 20 tons is enough, and for a large service station you need a hydraulic press of 50 tons. You can save money by making your own hands a press from a jack.