Any work with metal is impossible without a special cutting tool. If it is necessary to perform a single cutting or cutting a relative thin rod into a couple of millimeters, then you can do with a bulgarian, an electric jigsaw or a metal scissor. Thicker sheet metal and reinforcement are cut using hydraulic shears.
Principle of operation of hydraulic shears for cutting metal
On the device, the metal shears are largely similar to conventional manual or electric models. With the only difference is that the force on the moving knife is not transferred from the gearbox or the hand lever, but from the hydraulic cylinder, which is also called the pump. Such a design of the cutting tool offers a number of advantages:
- Due to the large conversion factor, the hydraulic scissors can develop a force of several tons on the cutting edge. At the same time, the weight of the mechanism does not exceed 1-4 kg;
- Significantly increased mobility and autonomy of the unit to perform the cut, no hydraulic drive is required for the hydraulic shears;
- Improved cut quality and single length of metal dissection;
- Hydraulic cutting with guillotine type of knives is much safer than traditional lever systems.
The main advantage of such tools is obvious. Unlike conventional scissors, hydraulic cutting metal develops an enormous force at the edge of the blades, which allows cutting the reinforcement and sheet metal quickly and accurately. This is important, for example, for the cutting of blanks from thick steel.
Typical design of hydraulic shears
The design of scissors for cutting metal is based on the principle of increasing the force with a hydraulic cylinder or pump. The operator applies a relatively small force of 10-15 kg to the lever of the pumping cylinder, while the working rod connected to the movable blade is capable of producing up to 4-5 tons for manual models and up to 50-60 tons for hydraulic press scissors.
Classes of hydraulic shears
The vast majority of hydraulic shear designs can be divided into three classes:
- Manual tools that allow the cutting of reinforcement, metal and cables. Here also the hydraulic scissors of emergency rescue services and household structures of hydraulic shears for cutting wire and rod are reckoned;
- Stationary or easel models, most often stationary machines with a hydraulic cylinder drive from a feeding pump station. Hydraulic shearing presses, apart from cutting metal, are able to perform several additional operations, such as piercing and cutting, so they are used mainly in the preparatory and press sections of machine-building plants;
- Hydraulic cutting systems, used in the construction, forestry and metallurgical industries.
The design of the open scissors is very similar to conventional sewing or stationery models. In such a system, two cutting blades connected on one axis during the metal cutting process under the action of pushing rods synchronously rotate towards each other and cut the material.
Guillotine scissors are made easier. One of the two blades is fixed immovably in the steel frame, the movable blade moves rectilinearly under the action of the hydraulic pusher. When two cutting edges meet, the metal is cut.
Hand tools for metal cutting, equipped with hydraulic booster
The most interesting are the manual designs of hydraulic shears. Guillotine variants of hydraulic shears are used only for cutting a rod or wire. This scheme allows you to more effectively distribute the cutting force, so guillotine systems are more compact and powerful.
In the production activity, both types of scissors are used, most often they are models WFD NGO- scissors hydraulic open, and NG - Devices with a guillotine arrangement of knives. The main difference is in the design of the hydraulic drive and the scheme of closing the knives.
Systems NGO - this is usually a hydraulic shears for cutting reinforcement, a complex profile pipe, rolled metal. They are heavier and larger than the guillotine. The cutting force on them is smaller, but due to the possibility of opening the blades they are able to cut the metal of any, the most complex profile. For example, the model NGO 100 is able to perform blade opening and capture the profile up to 100 mm.
Most emergency rescue and fire services tools use open-type hydraulic systems. In addition, such structures do not require preliminary preparation. It is enough to connect the instrument to the hydraulic pump and to grasp the cut metal profile.
Guillotine systems are most often used for cutting cables, cables and wires. The quality of the cutting line is higher, especially in the case of cutting thick stranded cables. In this case, the end section, consisting of a number of separate wires, under the pressure of the blades, seems to be welded into one mass. Such a cut does not pose a threat to others. The speed of the cutting is much less, as it is necessary to splint and partially disassemble the support frame to get the cable inside the guillotine.
The hydraulic drive of the manual scissors can be performed in three versions:
- In the form of a cylinder mounted on the body of a scissor with a swinging rod, most often this scheme is used for cutting cables;
- Remote floor version of the hydraulic cylinder with a lever drive from the foot or arm;
- In the form of a hydraulic pump equipped with an internal combustion engine.
In this case, the scissors are connected to an armored high-pressure hose. Controls of the drive with the hydraulic cylinder are located directly on the body of the scissors. For example, to relieve pressure and return the instrument to its original state, it will only be necessary to turn the working handle half a turn around its axis.
Powerful industrial scissors
A typical representative of hydraulic press scissors is the machine "MX 700 Nargesa". Scissors for cutting metal are designed in the form of a vertical console and a guillotine cutting module mounted on a metal frame.
The cutting force reaches 60-70 tons, which allows not only to cut the reinforcement or steel profile successfully, but also to bend, to work with pressure or to cut for black metal fittings. The dimensions of the working table allow processing workpieces with a height of up to 35 cm and a length of 60 cm. The hydraulic station is driven by an electric motor with a power of 5 kW.
Hydraulic shears of open type are widely used in construction and logging industries. A wide and powerful hydraulic gripper mounted on a heavy tractor effectively cuts concrete structures of buildings to be demolished, surgically cuts trees in urban plantations and easily cuts scrap of any configuration.
Metal cutting systems with hydraulics have the best force-to-weight ratio. Reliable and easy to maintain, the usual household models for cutting bars and fittings of good quality are designed for trouble-free operation for 3-4 years. Professional models are calculated on 3 thousand sections, after which it is necessary to change the seals and the valve hydraulic control system.
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